A ball is thrown straight upward. Which statement correctly describes the ball’s velocity and acceleration at the exact instant it reaches its highest point?
a) Its velocity is zero and its acceleration is zero.
b) Its velocity is directed downward with magnitude g and its acceleration is directed downward with magnitude g.
c) Its velocity is zero and its acceleration is directed downward with magnitude g.
d) Its velocity is zero and its acceleration is directed upward with magnitude g.