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': 'Circulus iridis major is seen at – \nSelect and explain. \nA. Ciliary body, B. Root of iris, C. Colarette of iris, D. Pupillary margin of iris', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Circulus arteriosus iridis major →Root of iris.\nCirculus arteriosum minor → At papillary margin of iris.', 'role': 'assistant'}]