As a White Dwarf Evolves,the Direction of Its Motion on the Herzsprung-Russell

As a white dwarf evolves,the direction of its motion on the Herzsprung-Russell diagram is from upper left to lower right,which means that:

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