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
Which is the most active single chemotherapeutic agent in the treatment of leiomyosarcoma ? 
Select and explain. 
A. Adriamycin, B. Daunorubicin, C. Methotrexate, D. Cisplatin
A: Adriamycin
Answer: A: Adriamycin 
Explanation: None