Please answer the following question: Information:  - An "n"-gonal bipyramid or dipyramid is a polyhedron formed by joining an "n"-gonal pyramid and its mirror image base-to-base. An "n"-gonal bipyramid has 2"n" triangle faces, 3"n" edges, and 2 + "n" vertices.  - Mathematics (from Greek  "máthma", knowledge, study, learning) is the study of topics such as quantity (numbers), structure, space, and change. There is a range of views among mathematicians and philosophers as to the exact scope and definition of mathematics.  - Space is the boundless three-dimensional extent in which objects and events have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime. The concept of space is considered to be of fundamental importance to an understanding of the physical universe. However, disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework.  - A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry. A triangle with vertices "A", "B", and "C" is denoted formula_1.  - In geometry , the gyroelongated bipyramids are an infinite set of polyhedra , constructed by elongating an n - gonal bipyramid by inserting an n - gonal antiprism between its congruent halves .  - Geometry (from the ; "geo-" "earth", "-metron" "measurement") is a branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space. A mathematician who works in the field of geometry is called a geometer.  - In elementary geometry, a polyhedron (plural polyhedra or polyhedrons) is a solid in three dimensions with flat polygonal faces, straight edges and sharp corners or vertices. The word polyhedron comes from the Classical Greek , as "poly-" (stem of , "many") + "-hedron" (form of , "base" or "seat").  - The Multinational Aircrew Electronic Warfare Tactics Facility Polygone - POLYGON is an Electronic Warfare Tactics Range located on the border between Germany and France. It is a tri-national facility operated by France, Germany and the United States.  - In geometry, a prismatoid is a polyhedron where all vertices lie in two parallel planes. Its lateral faces can be trapezoids or triangles. If both planes have the same number of vertices, and the lateral faces are either parallelograms or trapezoids, it is called a prismoid.  - A mirror image (in a plane mirror) is a reflected duplication of an object that appears almost identical, but is reversed in the direction perpendicular to the mirror surface. As an optical effect it results from reflection off of substances such as a mirror or water. It is also a concept in geometry and can be used as a conceptualization process for 3-D structures.  - In geometry, an "n"-sided antiprism is a polyhedron composed of two parallel copies of some particular "n"-sided polygon, connected by an alternating band of triangles. Antiprisms are a subclass of the prismatoids and are a (degenerate) type of snub polyhedra.     What object entity has the relation of 'subclass of' with the subject 'gyroelongated bipyramid'?   Choices: - bipyramid  - border  - branch  - c  - definition  - direction  - entity  - facility  - field  - geometry  - greek  - learning  - mathematician  - mathematics  - measurement  - mirror  - number  - perpendicular  - polygon  - polyhedron  - prismatoid  - process  - pyramid  - quantity  - range  - reflection  - seat  - space  - study  - subclass  - triangle  - warfare  - water
A:
polyhedron