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: Pediatrics
Most common type of congenital adrenal hyperplasis is 
Select and explain. 
A. 11 β Hydroxylase deficiency, B. 21 Hydroxylase deficiency, C. 17 α Hydroxylase deficiency, D. None of the above
B: 21 Hydroxylase deficiency
Answer: B: 21 Hydroxylase deficiency 
Explanation: None