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': 'Unilateral chronic conjunctivitis may be associated with \nSelect and explain. \nA. Habit of smoking, B. Use of uniocular microscope, C. Foreign body retained is the fornix, D. Unilateral aphakia', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. Foreign body retained is the fornix', 'role': 'assistant'}]