Let $f ( x ) = 7 \tan ^ { 8 } x + 7 \tan ^ { 6 } x - 3 \tan ^ { 4 } x - 3 \tan ^ { 2 } x$ for all $x \in \left( - \frac { \pi } { 2 } , \frac { \pi } { 2 } \right)$. Then the correct expression(s) is(are)\\
(A) $\quad \int _ { 0 } ^ { \pi / 4 } x f ( x ) d x = \frac { 1 } { 12 }$\\
(B) $\quad \int _ { 0 } ^ { \pi / 4 } f ( x ) d x = 0$\\
(C) $\int _ { 0 } ^ { \pi / 4 } x f ( x ) d x = \frac { 1 } { 6 }$\\
(D) $\int _ { 0 } ^ { \pi / 4 } f ( x ) d x = 1$