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: Pathology
[{'content': 'In myocardial infarction, light microscopic changes are evident by - \nSelect and explain. \nA. 1 hour, B. 1/2 hour, C. 6 hours, D. 24 hours', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., 1/2 hour", 'role': 'assistant'}]