This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: HAEM synth and porphyrias, Subject name: Biochemistry
[{'content': 'Heme is which porphyrin: \nSelect and explain. \nA. Type I, B. Type II, C. Type III, D. Type IV', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The side chain groups in porphyrins may be arranged in four different structural configurations (I to IV). Only type I and type III series are found in nature and the porphyrins of type III series are not only more abundant but are also physiologically impoant in humans. Haem is a type III porphyrin.', 'role': 'assistant'}]