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
[{'content': 'Episcleritis periodica refers to: \nSelect and explain. \nA. Fleeting type of episclerities, B. Complicated episcleis, C. Intermediate stage between episcleritis and scleritis, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Fleeting type of episclerities', 'role': 'assistant'}]