The most common cause of ambiguous genitalia in a newborn is -

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.