Consider a system represented by the block diagram shown below. Which of the following signal flow graphs represent(s) this system? Choose the correct option(s).

In the following block diagram, R(s) and D(s) are two inputs. The output Y(s) is expressed as Y(s) = G$$_1$$(s)R(s) + G$$_2$$(s)D(s).

G$$_1$$(s) and G$$_2$$(s) are given by

The signal flow graph for a system is given below. The transfer function $$\frac{Y(s)}{U(s)}$$ for this system is

Consider the signal flow graph shown in Figure. The gain $$\frac{x_5}{x_1}$$ is