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': "Investigations for carcinoma cervix in the early stage are all except : \nSelect and explain. \nA. Surface biopsy, B. Ultrasound, C. Colposcopic guided biopsy, D. Schiller's test", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ultrasound', 'role': 'assistant'}]