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: Social & Preventive Medicine
[{'content': 'Disadvantage of INH prophylaxis are all of the Following except \nSelect and explain. \nA. Cannot prevent disease in infected person, B. Not effective, C. Costly, D. Risk of hepatitis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]