This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Conjunctiva, Subject name: Ophthalmology
Phlyctenular conjunctivitis is caused by- 
Select and explain. 
A. Chlaymydia, B. Staphylococcus, C. Pneumococcus, D. Aspergillus
B: Staphylococcus
Answer: B: Staphylococcus 
Explanation: Causative allergens 1. Tuberculous proteins were considered, previously, as the most common cause. 2. Staphylococcus proteins are now thought to account for most of the cases. 3. Other allergens may be proteins of Moraxella Axenfeld bacillius and ceain parasites (worm infestation). ref: A K KHURANA OPHTALMOLOGY,E4, Page-77