If $\tan\alpha=\large\frac{1}{\sqrt{x(x^2+x+1)}}$,$\tan\beta=\large\frac{\sqrt x}{\sqrt{x^2+x+1}}$ and $\tan\gamma=\sqrt{x^{-3}+x^{-2}+x^{-1}}$ then $\alpha+\beta$ is

Question

$(a)\;\gamma\qquad(b)\;2\gamma\qquad(c_\;-\gamma\qquad(d)\;None\;of\;these$