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
Lallo, 25 yr old man, presented with h/o of pain redness & watering of left eye for last 1 day. There is also intolerance to light. Most probable diagnosis is: 
Select and explain. 
A. Keratitis, B. Acute anterior uveitis, C. Acute posterior uveitis, D. Epidemic kerato conjunctivitis
A: Keratitis
Answer: A: Keratitis 
Explanation: A i.e. Keratitis Pain and Photophobia i.e. intolerance to light results from stimulation of nerve endings Q that have become exposed in keratitis. So this is a characteristic feature of keratitis.