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': 'Extra retinal fibrovascular proliferation at ridge between normal and avascular retina is which grade of ROP? \nSelect and explain. \nA. ROP 1, B. ROP 2, C. ROP 3, D. ROP 4', 'role': 'user'}, {'content': 'Answer: C \nExplanation: ROP 3 REF: khurana 4th ed p. 265 Stages of ROP STAGE 1: Demarcation line STAGE 2: Demarcation ridge STAGE 3: Extra retinal proliferation and neovascularization STAGE 4: sub-retinal detachment including macula STAGE 5: Total retinal detachment', 'role': 'assistant'}]