This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Maternal Anatomy and Physiology, Subject name: Gynaecology & Obstetrics
[{'content': 'Shoest and narrowest pa of fallopian tube: \nSelect and explain. \nA. Interstitial, B. Isthmus, C. Ampulla, D. Infundibulum', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Pas of the fallopian tube Interstitial pa: shoest, internal diameter 1mm (narrowest) Isthmus:35 mm long, lumen diameter 2-3 mm Ampulla: 60-75 mm long, widest . Feilisation takes place here Infundibulum: where abdominal ostium opens into the peritoneal cavity', 'role': 'assistant'}]