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': 'Most sensitive method of quantitative measurement of human chorionic gonadotrophin : \nSelect and explain. \nA. Paper chromatography, B. Latex paicle test, C. Radio - immunoassay, D. Male toad test', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Radio - immunoassay', 'role': 'assistant'}]