Which statement about the Z-transform's region of convergence is true for a causal, stable system?

• A. The ROC outside the outermost pole and including the unit circle.
• B. The ROC is outside the outermost pole but never includes the unit circle.
• C. The ROC is inside the innermost pole.
• D. For a causal, stable system, the ROC is the entire z-plane.

Answer: (A)