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': 'Angiography of Choroidal melanoma shows \nSelect and explain. \nA. Collar stud appearance, B. Mushroom shape appearance, C. Double circulation, D. None of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Choroidal melanoma\nB-scan ⇒ Collar stud appearance / Mushroom shape appearance\nAngiography ⇒\xa0Double circulation', 'role': 'assistant'}]