Explanation:
We want to find the statement that is proven by the fact that the balls reach the same height.
A isn't supported by the evidence. Balls can reach the same height without having the same initial speed.
B isn't supported by the evidence. Balls can reach the same height without having the same launch angle.
C is supported. Projectiles spend the same amount of time going up as they do coming down, so if two projectiles reach the same height, then they must spend the same amount of time in the air.
D isn't supported by the evidence. Balls thrown at the same speed and complementary angles have the same range but different heights.
E isn't supported by the evidence. The mass of the ball doesn't affect the height.
