This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
An agent that activates natural killer cells and is useful in renal cell carcinoma is : 
Select and explain. 
A. Aldesleukin, B. Etanercept, C. Leflunomide, D. Thalidomide
A: Aldesleukin
Answer: A: Aldesleukin 
Explanation: Recombinant IL-2 (aldesleukin) is used for the treatment of malignant melanoma and renal cell carcinoma.