#### Answer

The correct answer is:
(d) neither the acceleration nor the velocity are zero

#### Work Step by Step

The correct answer is:
(d) neither the acceleration nor the velocity are zero
The horizontal component of velocity is constant, and since the ball follows a parabolic path, the horizontal component of velocity is non-zero. At the highest point, the vertical component of velocity is zero. However, because the horizontal component of velocity is non-zero, the velocity is also non-zero.
During the motion, the only force is the gravitational force, so the acceleration is $g$ during the whole motion. Therefore, the acceleration is non-zero at the highest point.