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': 'Most common characteristic of heat rupture: \nSelect and explain. \nA. Irregular margin, B. Smooth and well defined margin, C. Clot in wound, D. Vessels rupture', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Irregular margin', 'role': 'assistant'}]