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': 'Most common cause of anterior uveitis associated with ahritis: \nSelect and explain. \nA. Ankylosing spondylitis, B. Rheumatoid ahritis, C. Syphilis, D. Tuberculosis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Ankylosing spondylitis', 'role': 'assistant'}]