If $\tan\alpha=\large\frac{1}{7}$ and $\sin\beta=\large\frac{1}{\sqrt {10}}$ where $0\;<\alpha,\beta\;<\;\large\frac{\pi}{2}$ then $2\beta$ is equal to:

Question

$(a)\;\large\frac{\pi}{4}$$-\alpha\qquad(b)\;\large\frac{3\pi}{4}-$$\alpha\qquad(c)\;\large\frac{\pi}{8}$$-\alpha\qquad(d)\;\large\frac{3\pi}{8}-\frac{\alpha}{2}$