Answer
(d) The change in momentum of the ball is $2mv$.
Work Step by Step
Initial momentum of the ball, $\vec{p_i}=m\vec v$
After the ball hits the wall and bounces back, its velocity is $-v$.
Thus, final momentum, $\vec{p_f}=m(-\vec v)$.
Change in momentum, $\vec{p_i}-\vec{p_f}=2m\vec v$.
