A "Galactic Fountain" Is _____

A "galactic fountain" is _____.

A) a stream of gas and dust being pulled into a galaxy as it forms
B) a jet of high-speed superheated material thrown out of the accretion disk around a black hole
C) a partial spiral arm formed by the collision of molecular clouds
D) a bubble of hot, metal-rich gas ejected from the disk by a burst of supernova
E) a stream of gas made from a star that has been torn apart while falling into a supermassive black hole