A Rock Is Thrown at Some Angle Above the Horizontal

Multiple Choice

A rock is thrown at some angle above the horizontal with a certain velocity. It reaches its highest point and starts falling down. What is the velocity of the rock at the highest point of its trajectory?

A) 0
B) 9.8 m/s
C) It is equal to its initial horizontal velocity.
D) It is equal to its initial vertical velocity.
E) It is equal to its initial velocity.