This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cornea, Subject name: Ophthalmology
[{'content': 'In xerophthalmia classification X 2 stage is - \nSelect and explain. \nA. Bitots spots, B. Corneal xerosis, C. Corneal ulceration, D. Corneal scar', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Corneal xerosis WHO classification (1982)o The new xerophthalmia classification (modification of original 1976 classification) is as follows :XN Night blindnessXIA Conjunctival xerosisX1B Bitot's spotsX2 Corneal xerosisX3A Comeal ulceration/keratomalacia affecting less than one-third comeal surface.X3B Comeal ulceration/keratomalacia affecting more than one-third comeal surface.XS Corneal scar due to xerophthalmia XF Xerophthalmic fundus.", 'role': 'assistant'}]