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: Medicine
[{'content': 'The following agents may be used as prophylaxis in high altitude pulmonary edema - \nSelect and explain. \nA. ACE inhibitor, B. Acetazolamide, C. Nifedipine, D. Digoxin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]