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': 'Mucin layer tear flilm deficiency occurs in: \nSelect and explain. \nA. Keratoconjunctivitis sicca, B. Lacrimal gland removal, C. Canalicular block, D. Herpetic keratitis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e Keratoconjunctivitis sicca', 'role': 'assistant'}]