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: Biochemistry
[{'content': 'Chief regulator of systemic iron homeostasis: \nSelect and explain. \nA. Ferritin, B. Hepcidin, C. Haptoglobin, D. Transferrin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]