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: Gynaecology & Obstetrics
[{'content': 'In child with ambiguous genitalia, first test to be done is \nSelect and explain. \nA. Serum 17 hydroxy progesterone, B. Karyotyping, C. Serum 17 ketosteroid, D. Ultra sound pelvis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Karyotyping is first test to be done in child with ambiguous genitalia.', 'role': 'assistant'}]