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': 'Organism causing ulcus serpens is: \nSelect and explain. \nA. Neisseria gonorrhoeae, B. Corynebacterium diphtheria, C. Pneumococcus, D. Pseudomonas pyocyaneus', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ulcer serpens is caused by pneumococcus. Ulcer Serpens Greyish white ulcer Organism: Pneumococcus Usually associated with iridocyclitis Stas from periphery and then moves towards centre Has a tendency for perforation May be a/w hypopyon', 'role': 'assistant'}]