[单项选择]　　That large regions of the galaxy can be influenced by the formation of massive stars in a few localized regions requires that star formation somehow be coordinated over long periods of time. The process commences with a single O-type star or a cluster of such stars in a giant molecular cloud, around which stellar radiation, winds and explosions carve a modest cavity from of the surrounding interstellar medium, concomitantly destroying the progenitor cloud. Perchance this disturbance triggers star formation in a nearby cloud, and so on, until the interstellar medium in this corner of the galaxy resembles Swiss cheese, composed of what theorists have recently begun to refer to as bubbles, or superbubbles, one of the most exciting discoveries in astrophysics in years. Within a hot bubble, the sun has revealed itself in x-rays emitted by highly ionized trace ions such as oxygen and at some point in the process of its formation, nearby bubbles commence to overlap, coalescing into a superb
A. A star is discovered that emits lower levels of trace ions than those discovered by x-rays of our galaxy’’s sun.
B. A section of the universe is discovered to lack both stars and any sort of interstellar medium.
C. A galaxy is discovered with a negative rate of star formation.
D. In one corner of the galaxy, coronal gas is discovered to rarify as it becomes cooler.
E. A superbubble is found of equal mass to the galaxy surrounding it.