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: Skin
[{'content': 'M.C. cause of Nongonococcal Urethritis \nSelect and explain. \nA. Chlamydia, B. Mycoplasma, C. Trichomonas, D. Gram negative rod', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Chlamydia', 'role': 'assistant'}]