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': 'Lifespan of fetal RBC is ? \nSelect and explain. \nA. Same as adult RBC, B. 1/4 of adult RBC, C. 1/2 of adult RBC, D. 2/3 of adult RBC', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. is \'d\' i.e., 2/3 of adult RBC"Life span of fetal RBC is about 2/3\' of the adult RBC, i.e. about 80 days."', 'role': 'assistant'}]