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: Pathology
Tetrad of Urethritis, arthritis, conjunctivitis and oral ulcers seen in: 
Select and explain. 
A. Reiter's syndrome., B. Heerfordt syndrome., C. Behcet syndrome., D. Cowden syndrome.
A: Reiter's syndrome.
Answer: A: Reiter's syndrome. 
Explanation: None