Problem 2-43 - Free fall

A baseball pitcher throws a ball vertically straight upward and catches it $4.2\; s$ later. (a) With what velocity did the ball leave the pitcher's hand? (b) What was the maximum height reached by the ball?

This is a problem of motion taking place at:
 
(A)  constant velocity.

(B)  constant acceleration.

(C)  variable acceleration.