A realization of a stable discrete time system is shown in figure. If the system is excited by a unit step sequence input x[n], the response y[n] is

A. $$4{\left( { - \frac{1}{3}} \right)^n}u\left[ n \right] - 5{\left( { - \frac{2}{3}} \right)^n}u\left[ n \right]$$

B. $$5{\left( { - \frac{2}{3}} \right)^n}u\left[ n \right] - 3{\left( { - \frac{1}{3}} \right)^n}u\left[ n \right]$$

C. $$5{\left( { - \frac{1}{3}} \right)^n}u\left[ n \right] - 3{\left( { - \frac{2}{3}} \right)^n}u\left[ n \right]$$

D. $$5{\left( { - \frac{2}{3}} \right)^n}u\left[ n \right] - 5{\left( { - \frac{1}{3}} \right)^n}u\left[ n \right]$$

Answer: Option C