**Core Concept**
The question is testing the concept of immunosuppressive therapy in preventing organ rejection after transplantation. Specifically, it involves the use of monoclonal antibodies targeting T-cell surface antigens to modulate the immune response.

**Why the Correct Answer is Right**
The correct answer is a monoclonal antibody that targets CD25, also known as interleukin-2 receptor alpha (IL-2Rα). By binding to CD25, this antibody prevents the activation of T-cells, which are central to the immune response against transplanted organs. This mechanism of action is crucial in reducing the risk of acute organ rejection in adult patients. CD25 is a receptor for IL-2, a cytokine that promotes T-cell proliferation and activation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not target CD25 or IL-2Rα. Therefore, it would not be effective in preventing T-cell activation and organ rejection.

**Option B:** This option is incorrect because it is not a monoclonal antibody targeting CD25 or IL-2Rα. It may target other immune cells or mechanisms, but it is not the correct answer for this question.

**Option D:** This option is incorrect because it is not a well-known monoclonal antibody used for preventing acute organ rejection. It may be used for other indications or mechanisms, but it is not the correct answer for this question.

**Clinical Pearl / High-Yield Fact**
When considering immunosuppressive therapy for organ transplantation, it's essential to understand the different mechanisms of action, including T-cell modulation and cytokine blockade. This knowledge will help you choose the most effective treatment strategy for your patients.

**Correct Answer:** C. Basiliximab. Basiliximab is a monoclonal antibody that targets CD25 (IL-2Rα) and is used in the prophylaxis of acute organ rejection in adult patients.