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
[{'content': 'Drug containing two sulfhydryl groups in a molecule? \nSelect and explain. \nA. BAL, B. EDTA, C. Pencillamine, D. None of the above', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., BAL o Dimercaprol (British Anti-Lewisite, BAL) contains two sulfahydryl groups. Note - Penicillamine has one SH group.", 'role': 'assistant'}]