In "DAS BOAT", how did the crew raise the submarine from the bottom of the ocean?

Question

A) High Pressure air puched out the water from trimming tanks
B) The engines turned a propeller which pushed the submarine up.
C) The submarine fired a torpedo
D) Grappling gear was used.

Answer 1

Its been a few years since I watched the movie, but it definitely was not C or D. I'm pretty sure it was A.