This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2018, Subject name: Ophthalmology
True about Mooren's ulcer: 
Select and explain. 
A. Painless, B. Affects cornea, C. Sudden loss of vision, D. Bilateral in majority of cases
B: Affects cornea
Answer: B: Affects cornea 
Explanation: Mooren's ulcer Affects cornea Painful condition Slow loss of vision Mostly unilateral Peripheral corneal ulceration Clear cut overhanging edge seems to be melting from periphery