一个圆环,内圆半径是3cm,外圆半径是4cm,计算这个圆环面积的算式是请选择ABC3^3t-R3?0G(f6w2s7e4o*G(C2k6t0g8]3B9S+K
A.3.14×(42-32)(C2k6t0g8]3B9S+K
B.3.14×(4-3)2(C2k6t0g8]3B9S+K
C.3.14×(42+32)(C2k6t0g8]3B9S+K