A．R2、R3、R8B．Rl、R4、R7C．Rl、R2、R3、R5、R8D，R3、R7，R8

A．R2、R3、R8 B．Rl、R4、R7 C．Rl、R2、R3、R5、R8 D，R3、R7，R8

请帮忙给出正确答案和分析，谢谢！