This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Medicine
[{'content': 'Enzyme defect in acute intermittent porphyria \nSelect and explain. \nA. PMB deaminase, B. ALA dehydratase, C. UROI synthase, D. URO II synthase', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref - Davidsons 23e p378', 'role': 'assistant'}]