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: It is believed to be a delayed hypersensitivity (Type IV cell mediated) response to endogenous microbial proteins. Causative allergens are :- (i) Staphylococcus proteins (most common); (ii) Tuberculous proteins and (iii) Proteins of Moraxells axenfeld bacillus and ceain parasistes. Reference : AK Khurana 7th edition page 85