This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pelvic Inflammatory Disease, Subject name: Gynaecology & Obstetrics
PID is most commonly caused by - 
Select and explain. 
A. Chlamydia, B. Mycoplasma, C. Tubercular bacillus, D. E.Coli
A: Chlamydia
Answer: A: Chlamydia 
Explanation: Ans. is 'a' i.e., Chlamydia Sexually transmitted diseases are the most common cause of PIP.o Gonococcal & Chlamydial infections are the most common,o Mycoplasma hominis & genitalumo Tubercular bacilluso Viruseso E. colio Polymicrobial (both aerobe & anaerobs)