This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2019, Subject name: ENT
[{'content': 'Investigation used for CSF rhinorrhoea are all except \nSelect and explain. \nA. CT cisternogram, B. Skull X-ray, C. beta2 transferrin, D. Nasal endoscopy', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Advanced nasal endoscopic techniques can be used for CSF leak repair but not for investigation. CT cisternogram requires intrathecal injection of iohexol and a CT scan to localize the site. b 2 transferrin proteindetection by electrophoresis is asensitive and specific test for CSF.', 'role': 'assistant'}]