Given f(x) below, find f'(x). f(x) = ∫cos(x)ˣ⁴ t⁸ dt

(a) f'(x) = x³² - cos⁸(x)
(b) f'(x) = t⁹|cos(x)ˣ⁴
(c) f'(x) = x³² - cos⁹(x)
(d) f'(x) = 9x⁸ - cos⁸(x)