如下图所示求当N=0是，系统输出对输入的传递函数

2.png

A、
(G_4 (G_1 G_2+G_2 〖+G〗_3 ))/(1+G_4 (G_2-G_3))

B、
(G_4 (G_1 G_2+G_2 〖+G〗_3 ))/(1-G_4 (G_2+G_3))

C、
(G_4 (G_1 G_2-G_2 〖+G〗_3 ))/(1+G_4 (G_2+G_3))

D、
(G_4 (G_1 G_2+G_2 〖+G〗_3 ))/(1+G_4 (G_2+G_3))