This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
An organism not invading intact cornea- 
Select and explain. 
A. Gonococci, B. C. diphtheriae, C. Meningococci, D. Pseudomonas
D: Pseudomonas
Answer: D: Pseudomonas 
Explanation: Following three pathogens can invade the intact corneal epithelium and produce ulceration:

Neisseria gonorrhoea,
corynebacterium diphtheriae and 
Neisseria meningitidis.