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
The principal site for granulocytic hemopoiesis in the adult human is: 
Select and explain. 
A. The liver, B. The spleen, C. Red bone marrow, D. Yellow bone marrow
C: Red bone marrow
Answer: C: Red bone marrow 
Explanation: None