Please answer the following question: Information:  - A tool is any physical item that can be used to achieve a goal, especially if the item is not consumed in the process. Tool use by humans dates back millions of years, and other animals are also known to employ simple tools.  - Hardwood is wood from dicot angiosperm trees. The term may also be used for the trees from which the wood is derived; these are usually broad-leaved temperate and tropical forests. In temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen. Hardwood contrasts with softwood (which is from gymnosperm trees).   - In geography, latitude is a geographic coordinate that specifies the northsouth position of a point on the Earth's surface. Latitude is an angle (defined below) which ranges from 0° at the Equator to 90° (North or South) at the poles. Lines of constant latitude, or parallels, run eastwest as circles parallel to the equator. Latitude is used together with longitude to specify the precise location of features on the surface of the Earth. Approximations employed. Two levels of abstraction are employed in the definition of these coordinates. In the first step the physical surface is modelled by the geoid, a surface which approximates the mean sea level over the oceans and its continuation under the land masses. The second step is to approximate the geoid by a mathematically simpler reference surface. The simplest choice for the reference surface is a sphere, but the geoid is more accurately modelled by an ellipsoid. The definitions of latitude and longitude on such reference surfaces are detailed in the following sections. Lines of constant latitude and longitude together constitute a graticule on the reference surface. The latitude of a point on the "actual" surface is that of the corresponding point on the reference surface, the correspondence being along the normal to the reference surface which passes through the point on the physical surface. Latitude and longitude together with some specification of height constitute a geographic coordinate system as defined in the specification of the ISO 19111 standard.  - Softwood is wood from gymnosperm trees such as conifers. The term is opposed to hardwood, which is the wood from angiosperm trees.  - In botany, an evergreen is a plant that has leaves throughout the year, always green. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season. There are many different kinds of evergreen plants, both trees and shrubs. Evergreens include:  - Deciduous means "falling off at maturity" " or "tending to fall off", and it is typically used in order to refer to trees or shrubs that lose their leaves seasonally (most commonly during autumn) and to the shedding of other plant structures such as petals after flowering or fruit when ripe. In a more general sense, "deciduous" means "the dropping of a part that is no longer needed" or "falling away after its purpose is finished". In plants it is the result of natural processes. "Deciduous" has a similar meaning when referring to animal parts, such as deciduous antlers in deer or deciduous teeth, also known as baby teeth, in some mammals (including humans).  - Wood is a porous and fibrous structural tissue found in the stems and roots of trees, and other woody plants. It is an organic material, a natural composite of cellulose fibers which are strong in tension embedded in a matrix of lignin which resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees, or it is defined more broadly to include the same type of tissue elsewhere such as in the roots of trees or shrubs. In a living tree it performs a support function, enabling woody plants to grow large or to stand up by themselves. It also conveys water and nutrients between the leaves, other growing tissues, and the roots. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, or wood chips or fiber.  - In botany, a tree is a perennial plant with an elongated stem, or trunk, supporting branches and leaves in most species. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are usable as lumber or plants above a specified height. Trees are not a taxonomic group but include a variety of plant species that have independently evolved a woody trunk and branches as a way to tower above other plants to compete for sunlight. In looser senses, the taller palms, the tree ferns, bananas and bamboos are also trees. Trees tend to be long-lived, some reaching several thousand years old. The tallest known tree, a coast redwood named Hyperion, stands high. Trees have been in existence for 370 million years. It is estimated that there are just over 3 trillion mature trees in the world.  - The gymnosperms are a group of seed-producing plants that includes conifers, cycads, "Ginkgo", and gnetophytes. The term "gymnosperm" comes from the Greek composite word "" ( gymnos, "naked" and  sperma, "seed"), meaning "naked seeds", after the unenclosed condition of their seeds (called ovules in their unfertilized state). Their naked condition stands in contrast to the seeds and ovules of flowering plants (angiosperms), which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, often modified to form cones, or at the end of short stalks as in "Ginkgo".  - A hammer is a tool or device that delivers a blow (a sudden impact) to an object. Most hammers are hand tools used to drive nails, fit parts, forge metal, and break apart objects. Hammers vary in shape, size, and structure, depending on their purposes.  - The subtropics are geographic and climate zones located roughly between the tropic circle of latitude at 23.5 latitude (the Tropic of Cancer and Tropic of Capricorn) and temperate latitudes (normally temperate latitudes refer to locations higher than 40 latitude).  - A gavel is a small ceremonial mallet commonly made of hardwood , typically fashioned with a handle and often struck against a sound block , a striking surface typically also made of hardwood , to enhance its sounding qualities . It is a symbol of the authority and right to act officially in the capacity of a chair or presiding officer . The expression passing the gavel signifies an orderly succession from one chair to another . A gavel is used to call for attention or to punctuate rulings and proclamations . According to tradition , Vice President John Adams used a gavel to call the very first Senate to order in New York in the spring of 1789 . Since then , it has remained customary to rap the gavel against a lectern or desk to indicate the opening ( call to order ) and the closing ( adjournment ) of proceedings , giving rise to the phrase gavel - to - gavel to describe the entirety of a meeting or session . It is also used to keep the meeting itself calm and orderly . The sound of the gavel strike , being abrupt to start and stop , and clearly audible by all present , serves to sharply define an action in time in a manner clearly perceivable by all , and to endow the action with practical as well as symbolic finality . The gavel is used in courts of law in the United States and , by metonymy , is used there to represent the entire judiciary system , especially of judgeship ; to bring down the gavel means to enforce or compel with the power of a court . On the other hand , in the United Kingdom , gavels have never been used by judges , despite many American - influenced TV programmes depicting them . In addition , auctioneers have used gavels to signal a sale .  - The tropics are a region of the Earth surrounding the equator. They are delimited in latitude by the Tropic of Cancer in the Northern Hemisphere at  N and the Tropic of Capricorn in the Southern Hemisphere at  S; these latitudes correspond to the axial tilt of the Earth. The tropics are also referred to as the tropical zone and the torrid zone (see geographical zone). The tropics include all the areas on the Earth where the Sun is at a point directly overhead at least once during the solar year (which is a subsolar point).  - A mallet is a kind of hammer, often made of rubber or sometimes wood, that is smaller than a maul or beetle, and usually has a relatively large head. The term is descriptive of the overall size and proportions of the tool, and not the materials it may be made of, though most mallets have striking faces that are softer than steel.    Given the information above, choose from the list below the object entity that exhibits the relation 'subclass of' with the subject 'gavel'.  Choices: - being  - botany  - cancer  - circle  - circle of latitude  - climate  - condition  - coordinate system  - definition  - device  - fiber  - forge  - fruit  - general  - geography  - green  - group  - hammer  - hardwood  - height  - mallet  - material  - metal  - natural  - object  - order  - part  - plant  - point  - position  - process  - seed  - sense  - softwood  - species  - sphere  - state  - tissue  - tool  - tower  - tree  - type  - variety  - wood  - world  - year
A:
hammer