Let f (x) = 7tan8 x + 7tan6 x - 3tan4 x - 3tan2 x for all x ∈ \((-\frac{\pi}{2},\frac{\pi}{2})\). Then the correct expression(s) is(are)
(A) \(\int\limits_0^{\pi /4}\) xf (x) dx = 1/12
(B) \(\int\limits_0^{\pi /4}\) f(x)dx = 0
(C) \(\int\limits_0^{\pi /4}\) xf (x)dx = 1/6
(D) \(\int\limits_0^{\pi /4}\)f(x)dx = 1