This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
Lifespan of fetal RBC is- 
Select and explain. 
A. Same as adult RBC, B. 1/4 of adult RBC, C. 1/2 of adult RBC, D. 2/3 of adult RBC
D: 2/3 of adult RBC
Answer: D: 2/3 of adult RBC 
Explanation: Ans. (d) 2/3 of adult RBCRef: Ganong, 25th ed/p.555Life span of fetal RBCs is 60 to 90 days. It is about 2/3rd of adult RBCs life span