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': 'Investigation of choice in hyperprolactinemia is which of the following? \nSelect and explain. \nA. CT brain, B. MRI brain, C. Prolactin estimation, D. CH estimation', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The diagnosis of hyperprolactinemia is made by estimation of fasting morning prolactin.', 'role': 'assistant'}]