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': 'All are known to produce parenchymatous conjunctival xerosis except: \nSelect and explain. \nA. Vitamin A deficiency, B. Diphtheric membranous conjunctivitis, C. Trachoma, D. Stevens-Johnson syndrome', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Vitamin A deficiency', 'role': 'assistant'}]