Arock is thrown from the upper edge of a tall cliff at some angle above the horizontal. it reaches its highest point and starts falling down. which of the following statements about the rock's motion are true just before it hits the ground? a. its speed is the same as it was just as it was launchedb. its horizontal velocity component is the same as it was just as it was launchedc. its velocity is vertical. d. its vertical velocity component is the same as it was just as it was launched. e. its horizontal velocity component is zero.