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
Organism causing ulcus serpens is: 
Select and explain. 
A. Neisseria gonorrhoeae, B. Corynebacterium diphtheria, C. Pneumococcus, D. Pseudomonas pyocyaneus
C: Pneumococcus
Answer: C: Pneumococcus 
Explanation: 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