Write a search query that will help answer a complex question.

Follow the following format.

Question: ${the question to be answered}
Rationale: Let's think step by step. To answer this question, we first need to find out ${the missing information}
Search Query: ${a simple question for seeking the missing information}

Question: A 67-year-old man who was diagnosed with arthritis 16 years ago presents with right knee swelling and pain. His left knee was swollen a few weeks ago, but now with both joints affected, he has difficulty walking and feels frustrated. He also has back pain which makes it extremely difficult to move around and be active during the day. He says his pain significantly improves with rest. He also suffers from dandruff for which he uses special shampoos. Physical examination is notable for pitting of his nails. Which of the following is the most likely diagnosis? [options] A: Psoriatic arthritis B: Arthritis mutilans C: Rheumatoid arthritis D: Familial mediterranean fever E: Mixed connective tissue disease
Rationale: Let's think step by step. To answer this question, we first need to find out Write your response with at least 1000 words.
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