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
Commonest cause of ectopic pregnancy is : 
Select and explain. 
A. Endometriosis, B. Previous salpingitis, C. Anemia, D. Cervicitis
B: Previous salpingitis
Answer: B: Previous salpingitis 
Explanation: Previous salpingitis