Given the question: Pick one category for the following text. The options are - company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work. Vetehinen-class submarine -  The Vetehinen class submarine was a Finnish 500 tonne submarine class of three vessels that was designed and built in the 1920s and early 1930s. The Vetehinen class served in the Finnish Navy during World War II.
The answer is:
Mean Of Transportation