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': '16-year-old girl presents with rapid onset hirsutism and amenorrhea. Best investigation is: \nSelect and explain. \nA. Testosterone estimation, B. Dihydroepiandrosterone, C. Adrenocorticoids, D. LH and FSH estimation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]