This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Lens), Subject name: Ophthalmology
[{'content': 'Lens contains which antigen? \nSelect and explain. \nA. Sequestered antigens, B. Cross antigens, C. Heterophile antigens, D. Isoantigens', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ANSWER: (A) Sequestered antigensREF: Immunotoxicology and risk assessment By Dennis K. Flaherty p-182"Lens contains sequestered antigens"', 'role': 'assistant'}]