Ans. is 'c' i.e., IsthmusIsthmic and interstitial pregnancies have more chances of rupture while the ampullary pregnancies have more chances of tubal aboion.Out of the isthmic and interstitial ectopics, isthmic pregnancies have more chance of rupture as isthmic pregnancies are more common and wall of isthmic poion of the fallopian tube is narrow and less distensible and is easily eroded by chorionic viii.