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': 'Which glands does not contribute to Aqueous layer of tear film \nSelect and explain. \nA. Lacrimal, B. Accessory lacrimal, C. Wolfring, D. Zeis', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Zeis contributes to oil layer.', 'role': 'assistant'}]