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': 'Schirmer test is used for testing function of which of the following cranial nerve? \nSelect and explain. \nA. V, B. VII, C. IX, D. X', 'role': 'user'}, {'content': "Answer: B \nExplanation: The Schirmer test for the eye quantitatively measures tear formation placement of filter paper in the lower conjunctival sac. The test result is positive when less than 5 mm of paper is wetted after 5 minutes. It evaluates the function of the greater superficial petrosal branch. Ref: Chang D.F. (2011). Chapter 2. Ophthalmologic Examination. In P. Riordan-Eva, E.T. Cunningham, Jr. (Eds), Vaughan & Asbury's General Ophthalmology, 18e.", 'role': 'assistant'}]