Please answer the following question: Information:  - The London, Midland and Scottish Railway (LMS) was a British railway company. It was formed on 1 January 1923 under the Railways Act of 1921, which required the grouping of over 120 separate railways into four. The companies merged into the LMS included the London and North Western Railway, Midland Railway, the Lancashire and Yorkshire Railway (which had previously merged with the London and North Western Railway on 1 January 1922), several Scottish railway companies (including the Caledonian Railway), and numerous other, smaller ventures.  - Edinburgh is the capital city of Scotland and one of its 32 local government council areas. Located in Lothian on the Firth of Forth's southern shore, it is Scotland's second most populous city and the seventh most populous in the United Kingdom. The 2014 official population estimates are 464,990 for the city of Edinburgh, 492,680 for the local authority area, and 1,339,380 for the city region as of 2014 (Edinburgh lies at the heart of the proposed Edinburgh and South East Scotland city region). Recognised as the capital of Scotland since at least the 15th century, Edinburgh is home to the Scottish Parliament and the seat of the monarchy in Scotland. The city is also the annual venue of the General Assembly of the Church of Scotland and home to national institutions such as the National Museum of Scotland, the National Library of Scotland and the Scottish National Gallery. It is the largest financial centre in the UK after London.  - On a steam locomotive, a trailing wheel or trailing axle is generally an unpowered wheel or axle (wheelset) located behind the driving wheels. The axle of the trailing wheels is usually located in a trailing truck. On some large locomotives, a booster engine was mounted on the trailing truck to provide extra tractive effort when starting a heavy train and at low speeds on gradients.  - The Caledonian Railway (CR) was a major Scottish railway company. It was formed in the early 19th century with the objective of forming a link between English railways and Glasgow. It progressively extended its network soon reaching Edinburgh and Aberdeen, with a dense network of branch lines in the area surrounding Glasgow. It was absorbed into the London, Midland and Scottish Railway in 1923. Many of its principal routes continue active at the present day, and the original main line between Carlisle and Glasgow is in use as part of the West Coast Main Line railway (with a modified entry into Glasgow itself).  - The Caledonian Railway 300 Class were freight 0 - 6 - 0 tender engines introduced in 1918 and designed by William Pickersgill . Forty - three were built between 1918 and 1920 . They were numbered 294 -- 324 , 280 , 281 , 670 -- 679 by the Caledonian Railway .  - A tank locomotive or tank engine is a steam locomotive that carries its water in one or more on-board water tanks, instead of a more traditional tender. A tank engine may also have a bunker (or oil tank) to hold fuel. There are several different types of tank locomotive, distinguished by the position and style of the water tanks and fuel bunkers. The most common type has tanks mounted either side of the boiler. This type originated about 1840 and quickly became popular for industrial tasks, and later for shunting and shorter distance main line duties. Tank locomotives have advantages and disadvantages compared to traditional tender locomotives.  - Glasgow  is the largest city in Scotland, and third largest in the United Kingdom. Historically part of Lanarkshire, it is now one of the 32 council areas of Scotland. It is situated on the River Clyde in the country's West Central Lowlands. Inhabitants of the city are referred to as Glaswegians.  - On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons (or turbine, in the case of a steam turbine locomotive). On a conventional, non-articulated locomotive, the driving wheels are all coupled together with side rods (also known as coupling rods); normally one pair is directly driven by the main rod (or connecting rod) which is connected to the end of the piston rod; power is transmitted to the others through the side rods.  - In rail transport, a wheel arrangement or wheel configuration is a system of classifying the way in which wheels are distributed under a locomotive. Several notations exist to describe the wheel assemblies of a locomotive by type, position, and connections, with the adopted notations varying by country. Within a given country, different notations may also be employed for different kinds of locomotives, such as steam, electric, and diesel powered.  - Aberdeen  is Scotland's third most populous city, one of Scotland's 32 local government council areas and the United Kingdom's 37th most populous built-up area, with an official population estimate of 196,670 for the city of Aberdeen itself and 228,990 for the local authority area. Aberdeen is the Oil Capital of the World.   - The West Coast Main Line (WCML) is the most important intercity rail passenger route in the United Kingdom, connecting the major cities of London, Birmingham, Coventry, Edinburgh, Glasgow, Liverpool and Manchester. which have a combined metropolitan population of over 24 million people. In addition, several sections of the WCML form part of the suburban railway systems in London, Birmingham, Manchester and Glasgow, with many more smaller commuter stations, as well as providing links to more rural towns. In 2008 the WCML handled 75 million passenger journeys.  - A steam locomotive is a railway locomotive that produces its pulling power through a steam engine. These locomotives are fueled by burning combustible materialusually coal/coke, wood, or oilto produce steam in a boiler. The steam moves reciprocating pistons which are mechanically connected to the locomotive's main wheels (drivers). Both fuel and water supplies are carried with the locomotive, either on the locomotive itself or in wagons (tenders) pulled behind. The first steam locomotive, made by Richard Trevithick, first operated on 21 February 1804, three years after the road locomotive he made in 1801. The first practical steam locomotive was built in 1812-13 by John Blenkinsop.  - Chief mechanical engineer and locomotive superintendent are titles applied by British, Australian, and New Zealand railway companies to the person ultimately responsible to the board of the company for the building and maintaining of the locomotives and rolling stock. In Britain, the post of "locomotive superintendent" was introduced in the late 1830s, and "chief mechanical engineer" in 1886.  - The Whyte notation for classifying steam locomotives by wheel arrangement was devised by Frederick Methvan Whyte, and came into use in the early twentieth century following a December 1900 editorial in "American Engineer and Railroad Journal". The notation counts the number of leading wheels, then the number of driving wheels, and finally the number of trailing wheels, groups of numbers being separated by dashes. Other classification schemes, like UIC classification and the French, Turkish and Swiss systems for steam locomotives, count axles rather than wheels.  - William Pickersgill (1861  2 May 1928) was chief mechanical engineer of the Caledonian Railway from 1914 until Grouping in 1923. He was appointed locomotive superintendent of the Northern Division of the London, Midland and Scottish Railway but retired in 1925. He died in Bournemouth.  - Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles and no trailing wheels. This was the most common wheel arrangement used on both tender and tank locomotives in versions with both inside and outside cylinders.  - Bournemouth is a large coastal resort town on the south coast of England directly to the east of the Jurassic Coast, a World Heritage Site. According to the 2011 census, the town has a population of 183,491 making it the largest settlement in Dorset. With Poole to the west and Christchurch in the east, Bournemouth forms the South East Dorset conurbation, which has a total population of over 465,000.    After reading the paragraphs above, we are interested in knowing the entity with which 'caledonian railway 300 class' exhibits the relationship of 'subclass of'. Find the answer from the choices below.  Choices: - articulated locomotive  - being  - board  - branch  - capital  - case  - city  - coast  - country  - coupling  - distance  - editorial  - engineer  - england  - english  - financial centre  - french  - heart  - home  - jurassic  - line  - link  - locomotive  - material  - monarchy  - museum  - network  - notation  - objective  - oil  - part  - person  - rail  - rail transport  - railway company  - resort town  - rod  - seat  - second  - steam engine  - stock  - style  - tank  - third  - train  - truck  - turbine  - turkish  - venue  - water  - western  - wheel  - wood
A:
locomotive