|A) continue going upwards uninterrupted||B) reach a particular height and remain floating|
|C) burst after reaching some height||D) reach a particular height and start coming down|
It will stop at a height where the weight of the balloon with contents is equal to the weight of air displaced by it, i.e , when the upthrust is equal to the downthrust. The question of bursting will depend on how much difference of pressure inside and outside , the material of the balloon can withstand. It is assumed the balloon is filled with a lighter than air gas like hydrogen or helium.