Solve $3\tan(\theta-15^{\large\circ})=\tan(\theta+15^{\large\circ})$

Question

$\begin{array}{1 1}(A)\;\large\frac{n\pi}{2}\normalsize +(-1)^n\large\frac{\pi}{4}&(B)\;n\pi\pm \large\frac{\pi}{6}\\(C)\;n\pi\pm \large\frac{\pi}{8}&(D)\;2n\pi\pm \large\frac{3\pi}{4}\end{array}$