This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
[{'content': 'In Heme synthesis, which of the following is inhibited by LEAD? \nSelect and explain. \nA. Xanthine oxidase, B. ALA dehydratase, C. ALA synthase, D. Uroporphyrin synthase', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Lead inhibits ALA dehydratase and ferrochelatase, preventing incorporation of iron and causing anemia and porphyria.', 'role': 'assistant'}]