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: Physiology
[{'content': 'The principal site for granulocytic hemopoiesis in the adult human is: \nSelect and explain. \nA. The liver, B. The spleen, C. Red bone marrow, D. Yellow bone marrow', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]