Cho

Câu hỏi: Cho ${\int }_0^{\frac{\mathrm{\pi }}{2}}f\left(x\right) \sin x dx = {\int }_0^{\frac{\mathrm{\pi }}{2}}f\text{'}\text{'}\left(x\right).\sin x dx = f\left(0\right) = 1$ Tính $f\text{'}\left(\frac{\mathrm{\pi }}{2}\right)$

A. 1.

B. 0

C. -1

D. 2.