Answer
Choice c.
Work Step by Step
Choice A is incorrect because the acceleration is downward with magnitude g.
Choice B is incorrect because there must be a horizontal component of velocity: the ball didn’t travel straight up. This horizontal component stays constant, so the ball’s overall velocity is never zero.
At the highest point of its motion, the vertical component of the ball’s velocity is zero, while the horizontal component stayed constant all along. Thus, the magnitude of the ball’s velocity is minimum there. Choice C is true.