Two particles are executing simple harmonic motion of the same amplitude A and frequency $\omega$ along the $x$ axis. Their mean position is separated by distance $X_{0}\left(X_{0}>A\right)$. If the maximum separation between them is $\left(X_{0}+A\right)$, the phase difference between their motion is:\\
(1) $\frac{\pi}{3}$\\
(2) $\frac{\pi}{4}$\\
(3) $\frac{\pi}{6}$\\
(4) $\frac{\pi}{2}$