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
Regarding spring catarrh, all of the following are true, except: 
Select and explain. 
A. Cobblestone appearance of conjunctiva, B. Common in spring months, C. Limbus conjunctival thickening, D. Sodium cromoglycate is a form of therapy
C: Limbus conjunctival thickening
Answer: C: Limbus conjunctival thickening 
Explanation: Limbus conjunctival thickening