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
Basic defect in HbS is - 
Select and explain. 
A. Altered function, B. Altered solubility, C. Altered stability, D. Altered O2 binding capacity
B: Altered solubility
Answer: B: Altered solubility 
Explanation: None