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
Sterilization is commonly performed at which site of fallopian tube: 
Select and explain. 
A. Ampulla, B. Infundibulum, C. Isthmus, D. Cornua
C: Isthmus
Answer: C: Isthmus 
Explanation: I have given these 2 questions simultaneously so that you understand how the answer changes as the options of the question change. Sterilization is done at the junction of proximal and middle third—the loop formed consists mainly of isthmus and part of the ampullary region of the tube.
Therefore, if in options isthmoampullary is given, it is the best choice but if isthmoampullary is not given Isthmus is the next best choice.