The Nova Phenomenon, an Occasional and Sometimes Repeated Intense Brightening

The nova phenomenon, an occasional and sometimes repeated intense brightening of a star by a factor of about 10⁶, is caused by

A) a beam of radiation from a nearby pulsar illuminating the surface of a red giant star and inducing rapid and intense heating.
B) the capture and rapid compression of matter by a black hole.
C) the explosion of a single massive star at the end of its thermonuclear fusion phases.
D) explosive hydrogen fusion on the surface of a white dwarf star after mass transfer from a companion star in a binary system.