For a negative feedback system shown in figure,

the equivalent transfer function is :

A

$$\frac{s^{3}+5s^{2}+6s}{s^{3}+7s^{2}+12s+3}$$

B

$$\frac{s^{3}+5s^{2}+6s}{s^{3}+5s^{2}+4s-3}$$

C

$$\frac{s^{3}+5s+4}{s^{3}+7s^{2}+12s+3}$$

D

$$\frac{s^{3}+5s+4}{s^{3}+7s^{2}+4s-3}$$