The Mechanism That Gives Rise to the Phenomenon of the Nova

Multiple Choice

The mechanism that gives rise to the phenomenon of the nova is

A) the impact and subsequent explosion of a large comet nucleus on a star's surface.
B) material falling into a black hole and being condensed to the point where a thermonuclear explosion is produced.
C) the complete disintegration of a massive star due to a runaway thermonuclear explosion in the star's interior.
D) matter from a companion star falling onto a white dwarf in a close binary system, eventually causing a nuclear explosion on the dwarf's surface.