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
Longest life span among following ? 
Select and explain. 
A. RBC, B. Plalalets, C. Neutrophils, D. Macrophages
D: Macrophages
Answer: D: Macrophages 
Explanation: Ans. is 'd' i.e., Macrophages