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
The most common systemic association of scleritis is – 
Select and explain. 
A. Ehlers – Danlos syndrome, B. Disseminated systemic sclerosis, C. Rheumatiod arthritis, D. Giant cell arteritis
C: Rheumatiod arthritis
Answer: C: Rheumatiod arthritis 
Explanation: "When a patient comes to an ophthalmologist with scleritis, RA must be considered, because it is the most common cause of scleritis (and episcleritis)".
— The cornea by Dohlman