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': 'Corneal dystrophies are usually – \nSelect and explain. \nA. Primarily unilateral, B. Primarily bilateral, C. Primarily unilateral without systemic disease, D. Primarily bilateral with systemic disease', 'role': 'user'}, {'content': 'Answer: B \nExplanation: "A corneal dystrophy is classically bilateral, progressive, and isolated to the cornea. The disorder is inherited, characteristically in a dominant fashion, and often appears clinically to involve only one layer of the cornea "...Yanoff', 'role': 'assistant'}]