This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pediatrics
[{'content': 'Most common cause of congenital adrenal hyperplasia? \nSelect and explain. \nA. 17- Hydroxylase deficiency, B. 11- Hydroxylase deficiency, C. 21- Hydroxylase deficiency, D. 16- Hydroxylase deficiency', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. c (21- Hydroxylase deficiency). (Ref. Harrison, Principles of Medicine, 18th/2178)Congenital adrenal hyperplasia (CAH)Features3-beta-OH21-OH11-beta-OH17-alpha-OH1. Salt loss++ 2. Hypertension -++3. Virilization-++-4. Ambigous genitaliaa) Male+__+b) Female+++-Note: 21-hydroxylase deficiency is the most common type of CAH', 'role': 'assistant'}]