As a White Dwarf Evolves, the Direction of Its Motion

Multiple Choice

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

A) it cools and becomes more luminous.
B) it cools and becomes less luminous.
C) it heats up and becomes more luminous.
D) it heats up and becomes less luminous.