Answer the following question: USS S-21 (SS-126) - USS S-21 (SS-126) was a first-group (S-1 or Holland) S-class submarine of the United States Navy. Her keel was laid down on 19 December 1918 by the Bethlehem Shipbuilding Corporation in Quincy Massachusetts. She was launched on 18 August 1920 sponsored by Mrs. Thomas Baxter and commissioned on 24 August 1921 with Lieutenant R. P. Luker in command. 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?
Answer:
Mean Of Transportation