This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
[{'content': 'In sickle cell anemia \nSelect and explain. \nA. Glutamate replaces valine, B. Valine replaces glutamate, C. Valine replaces aspaate, D. Aspaate replaces valine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Sickle cell anemia is caused by mutation in the beta globin chain, that changes the amino acid glutamate to valine in the 6th position of beta globin chain of HbRef: Textbook of medical physiology by N Geetha, 3rd edition, page no. 94', 'role': 'assistant'}]