Answer
Choice D.
Work Step by Step
The stone slows down, and moves slowest at the very top of its flight. The speed at maximum height is $v_ocos \theta_o$, and is nonzero.
The vertical velocity component is zero, and the horizontal component is the same as at the time of launch. As the stone falls, the speed increases again, and exceeds the initial speed as the stone falls to below its initial height.
This behavior is shown only in Graph D.
