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': 'Persistant pupillary membrane originates from \nSelect and explain. \nA. Collarete, B. Around pupil, C. Angle of anterior chamber, D. Root of iris', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Persistant pupillary membrane\n\nDevelopmental abnormality of iris.\nStarts at iris collarette (thickest part of iris).', 'role': 'assistant'}]