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
In a mutation, if valine is replaced by which of the following, would not result in any change in the function of the protein 
Select and explain. 
A. Proline, B. Leucine, C. Glycine, D. Aspartic acid
D: Aspartic acid
Answer: D: Aspartic acid 
Explanation: Normally functional hemoglobin may have different AA at position 67 of β-chain in place of valine.