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: Dental
[{'content': 'Porphyrins are synthesized mainly in - \nSelect and explain. \nA. Spleen, B. Liver and spleen, C. Bone marrow and spleen, D. Liver and bone marrow', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Porphyrins are synthesized in - Liver, Bone marrow.', 'role': 'assistant'}]