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
[{'content': 'The most common cause of ambiguous genitalia in a newborn is - \nSelect and explain. \nA. 21 hydroxylase deficinece, B. 11 beta - hydroxylase deficiency, C. 17 alpha - hydroxyalse deficiency, D. 3 beta - hydroxysteroid deficiency', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., 21 hydroxylase deficiency o Congenital adrenal hyperplasia due to classic 21-Hydroxylase deficiency is the most common cause of ambiguous genitalia in the newborn. Virilization is apparent at bih in the female and within the first 2-3 years of life in the male.", 'role': 'assistant'}]