A line makes angle $\theta$ with both $x\:axis$ and $z\:axis$. If it makes angle $\alpha$ with $y\:axis$ and $\sin^2\alpha=2 \sin^2\theta$ then $\cot^2\theta=?$

Question

$(a)\;2/3\:\:\:\qquad\:\:(b)\:\:1\:\:\:\qquad\:\:(c)\:\:3/5\:\:\:\qquad\:\:(d)\:\:5/3$