Q:Type AM submarine -  The AM (A Modified) type submarine was a large seaplane-carrying submarine of the Imperial Japanese Navy with a hangar space for 2 aircraft. These giant submarines were originally of the A2 type meant to act as command boats for groups of submarines but their design was revised after construction started so that they could carry a second aircraft. 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