Let $I_n = \int \tan^n x\; dx, \; (n > 1)$. If $I_4 + I_6 = a \tan^5 x + bx^5 + C$, where $C$ is a constant of integration, then the ordered pair $(a, b)$ is equal to

Question

( A ) $(\frac{1}{5}, -1)$
( B ) $(-\frac{1}{5}, 1)$
( C ) $(\frac{1}{5}, 0)$
( D ) $(-\frac{1}{5}, 0)$