A Nova Is a Sudden Brightening of a Star That

A nova is a sudden brightening of a star that occurs when

A) material is transferred onto the surface of a white dwarf from a companion star in a binary system, then subsequently blasted into space by a runaway thermonuclear explosion (leaving the white dwarf intact to repeat the process) .
B) material from a companion star is transferred onto the surface of a white dwarf star in a binary system, after which runaway carbon-fusion reactions cause the entire white dwarf to be destroyed in an explosion.
C) the electron degenerate iron core of a massive star collapses after its mass becomes greater than the Chandrasekhar mass limit.
D) material is transferred onto a neutron star from a companion star in a binary system, causing the neutron star to collapse into a black hole.