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: Anatomy
[{'content': 'Referred pain in external haemorrhoids is due to - \nSelect and explain. \nA. Common pudendal nerve, B. Inferior rectal nerve, C. Splanchnic nerve, D. Sympathetic nerve', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Pain sensation below the pectinate line is carried by inferior rectal nerve, a branch of pudendal nerve.', 'role': 'assistant'}]