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': 'Pigment deposition on cornea seen in: \nSelect and explain. \nA. Chloroquine, B. Digoxin, C. Ranitidine, D. All', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Chloroquine', 'role': 'assistant'}]