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: Biochemistry
Which of the following can be a homologous substitution for valine in hemoglobin 
Select and explain. 
A. Isoleucine, B. Glutamic acid, C. Phenylalanine, D. Lysine
B: Glutamic acid
Answer: B: Glutamic acid 
Explanation: None