All of These Are Possible Mechanisms Believed to Be Capable

Multiple Choice

All of these are possible mechanisms believed to be capable of triggering the collapse of a cloud of gas and dust to form stars EXCEPT

A) stellar winds may compress nearby gas and dust clouds.
B) a nearby supernova can compress nearby gas and dust clouds.
C) clouds can collide and compress each other.
D) radiation pressure from the cosmic microwave background can compress clouds of gas and dust.