For `x in (0,(5pi)/(2))`, defined `f(x) = int_(0)^(x) sqrt(t)sint dt`. Then f has:
A. local maximum at `pi` an d `2pi`.
B. local minimum at `pi` an d `2pi`.
C. local maximum at `pi` and local maximum at `2pi`.
D. local maximum at `pi` and local minimum at `2pi`.