Q:German submarine U-561 - German submarine U-561 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II.She was laid down on 28 February 1940 by Blohm & Voss in Hamburg as 'werk' 537 launched on 23 January 1941 and commissioned on 13 March 1941 under Kapitanleutnant Robert Bartels (German Cross in Gold). Given a choice of categories company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work, the text refers to which one?
A:
Mean Of Transportation