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: Pediatrics
Bart hemoglobin consist of 
Select and explain. 
A. Four γ chains, B. Four β chains, C. Two γ chains + Two β chains, D. Two α chains + Two γ chains
A: Four γ chains
Answer: A: Four γ chains 
Explanation: Bart hemoglobin is tetramer of four γ chains.