This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immune system, Subject name: Medicine
[{'content': "All of the following are asociated with secondary Sjogren's syndrome EXCEPT \nSelect and explain. \nA. Rheumatoid ahritis, B. Primary biliary cirrhosis, C. Pheochromocytoma, D. Systemic lupus erythematosus", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ref - researchgate.net', 'role': 'assistant'}]