The region of convergence of z-transform of the sequence
$${\left( {{5 \over 6}} \right)^n}u\left( n \right) - {\left( {{6 \over 5}} \right)^n}u\left( { - n - 1} \right)$$      must be

A. $$\left| z \right| < {5 \over 6}$$

B. $$\left| z \right| > {5 \over 6}$$

C. $${5 \over 6} < \left| z \right| < {6 \over 5}$$

D. $${6 \over 5} < \left| z \right| < \infty $$

Answer: Option C