One Peculiar Feature of the Evolution of a White Dwarf

One peculiar feature of the evolution of a white dwarf star is that:

A) its size or radius slowly increases as it cools, until it becomes a red giant star.
B) it heats as it shrinks because of the release of gravitational energy, ending up as a very hot but very small star.
C) it shrinks as it cools, eventually to become a cold black hole in space.
D) its size remains constant as it cools and dies.