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: Gynaecology & Obstetrics
Non-gonococcal urethritis is caused by: 
Select and explain. 
A. Chlamydia, B. LGV, C. Syphilis, D. Gardnerella vaginalis
A: Chlamydia
Answer: A: Chlamydia 
Explanation: None