The D-Type commonly known as the Triplex is a retired New York City Subway car with four units built as a prototype in 1925 and the production units built during 1927 and 1928. Given a list of categories: company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work, what category does the paragraph belong to?
Answer:
Mean Of Transportation