This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Lens, Subject name: Ophthalmology
[{'content': 'Onion peel appearance cataract is seen in which of the following types? \nSelect and explain. \nA. Posterior subcapsular cataract, B. Anterior subcapsular cataract, C. Posterior polar cataract, D. Anterior polar cataract', 'role': 'user'}, {'content': "Answer: C \nExplanation: Posterior polar cataract Caused by persistence of the hyaloids aery. Strong adherence of the opacity to the weak posterior capsule Can be stationary as well as progressive type 1) Stationary-well circumscribed circular opacity localized on the central posterior capsule. Concentric thickened rings around the central plaque opaciy are seen (Bull's eye. onion peel appearance). 2) Progressive type-whitish opacification in the posterior coex (radiating rider opacity). Feather and scalloped appearance is seen. (Ref: researchgate.net)", 'role': 'assistant'}]