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: Pathology
In sickle cell anemia there is substitution of 
Select and explain. 
A. Valine for glutamic acid at the sixth position of beta chain, B. Phenylalanine for glutamic acid, C. Tyrosine for valine at the 6th position at beta chain, D. All of the above
A: Valine for glutamic acid at the sixth position of beta chain
Answer: A: Valine for glutamic acid at the sixth position of beta chain 
Explanation: None