Find the inverse Z- Transform of (( frac{z}{z-a})^3 ).

• A. ( frac{1}{2} . (n+1) (n-2) a^{n-2} U(n) )
• B. ( frac{1}{2} . (n-1) (n-2) a^{n-3} U(n) )
• C. ( frac{1}{2} . (n-1) (n+2) a^{n-1} U(n) )
• D. ( frac{1}{2} . (n+1) (n+2) a^n U(n) )