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
Spring catarrh is – 
Select and explain. 
A. Type I hypersensitivity reaction, B. Type II hypersensitivity reaction, C. Type III hypersensitivity reaction, D. Type IV hypersensitivity reaction
A: Type I hypersensitivity reaction
Answer: A: Type I hypersensitivity reaction 
Explanation: Spring catarrh is a type I hypersensitivity to exogenous allergens.