The value of z{[k-1] u(k)} is _______________

• A. \(\frac{z(z+2)}{(z-1)^2}\)
• B. \(\frac{2z-z^2}{(z-1)^2}\)
• C. \(\frac{z^2}{(z-1)^2}\)
• D. \(\frac{z(z-2)}{(z+1)^2}\)