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: Surgery
[{'content': "Investigation of choice in hirschsprug's disease is ? \nSelect and explain. \nA. Rectal manometry, B. Rectal examination, C. Rectal biopsy, D. Ba enema", 'role': 'user'}, {'content': "Answer: C \nExplanation: Answer 'c' i.e. Rectal biopsy Definitive diagnosis is made by rectal biopsy. The histopathology of Hirschprung's disease is the absence of ganglion cells in the nerve plexus, presence of hyperophied nerve bundles and increased acetylcholinesterase-positive nerve fibres.", 'role': 'assistant'}]