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: Ophthalmology
[{'content': 'In fundus, first sign of raised intracranial pressure is: \nSelect and explain. \nA. Filling of physiological cup, B. Blurring of nasal disc, C. Dilatation of vessels, D. None of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. Dilatation of vessels', 'role': 'assistant'}]