39. A ball which is dropped from the top of a building strikes the ground with a speed of 30m/s. Assume air resistance can be ignored. The height of the building is approximately:
(A) 15 m
(B) 30 m
(C) 45 m
(D) 75 m
(A) 15 m
(B) 30 m
(C) 45 m
(D) 75 m