The signal flow graph for a system is given below. The transfer function  $\dfrac{Y(s)}{U(s)}$  for this system is
1. $\dfrac{s+1}{5s^2+6s+2}$
2. $\dfrac{s+1}{s^2+6s+2}$
3. $\dfrac{s+1}{s^2+4s+2}$
4. $\dfrac{1}{5s^2+6s+2}$