The Figure Shows Two Waves Traveling in the Positive-X Direction $\pi$

Multiple Choice

The figure shows two waves traveling in the positive-x direction. The phase difference between these two waves is

A) $\pi$ radians.
B) $\pi$ /2 radians.
C) $\pi$ /4 radians.
D) $\pi$ /8 radians.
E) $\pi$ /16 radians.