设函数f(u)连续,区域D={(x,y)|x^2+y^2≤2y},则等于( )。
A A.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251114/23827725_0_2.png"> B
B.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251114/23827725_0_3.png"> C
C.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251114/23827725_0_4.png"> D
D.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251114/23827725_0_5.png">