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: Medicine
Bart hemoglobin is a tetramer of 
Select and explain. 
A. γ globin, B. β globin, C. α globin, D. δ globin
A: γ globin
Answer: A: γ globin 
Explanation: Bart Hb is a tetramer of excess γ globin.