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: Medicine
[{'content': 'Most common complication of rubella- \nSelect and explain. \nA. Polyarthritis, B. Encephalitis, C. Orchitis, D. Thromobocytopenia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]