**Core Concept**
Post-renal transplant patients require immunosuppressive therapy to prevent rejection of the transplanted organ. The triple therapy regimen typically includes a combination of drugs that work synergistically to suppress the immune system.

**Why the Correct Answer is Right**
The triple therapy regimen for post-renal transplant patients usually consists of a calcineurin inhibitor (e.g., cyclosporine or tacrolimus), an antiproliferative agent (e.g., azathioprine or mycophenolate mofetil), and a corticosteroid (e.g., prednisone). This combination of drugs helps to prevent rejection by suppressing T-cell activation, proliferation, and function.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because cyclosporine is a calcineurin inhibitor that is commonly used in the triple therapy regimen.
* **Option B:** This option is incorrect because azathioprine is an antiproliferative agent that is often used in combination with other drugs to prevent rejection.
* **Option C:** This option is incorrect because prednisone is a corticosteroid that is typically used in the triple therapy regimen to suppress inflammation and immune response.

**Clinical Pearl / High-Yield Fact**
One important aspect of immunosuppressive therapy in post-renal transplant patients is the need for careful monitoring of drug levels and side effects. This includes regular blood tests to check for signs of toxicity or rejection, as well as adjustments to the medication regimen as needed to minimize adverse effects.

**Correct Answer: D.**