For the closed-loop system shown, the transfer function $\dfrac{E\left ( s \right )}{R\left ( s \right )}$ is
1. $\frac{G}{1+GH}$
2. $\frac{GH}{1+GH}$
3. $\frac{1}{1+GH}$
4. $\frac{1}{1+G}$