Please answer the following question: SM U-106 was one of the 329 submarines serving in the Imperial German Navy in World War I. U-106 was commissioned on 28 Jul 1917 under the command of Kapitanleutnant Hans Hufnagel and participated in one wartime patrol starting on 2 September 1917. On 18 September 1917 during the First Battle of the Atlantic U-106 was credited with the sinking of HMS Contest an Acasta class destroyer and damaging City of Lincoln a 5867 ton steamer in the Western Approaches. 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?
A:
Mean Of Transportation