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
Which of the following cells become tissue macrophages 
Select and explain. 
A. Neutrophils, B. Eosinophils, C. Monocytes, D. Lymphocytes
C: Monocytes
Answer: C: Monocytes 
Explanation: Monocytes enter the blood from the bone marrow and circulate for about 72 hours. They then enter the tissues and become tissue macrophages.
Ganong 23 rd ed, pg 65