What Is the Difference Between Dark Matter and Dark Energy

Multiple Choice

What is the difference between dark matter and dark energy?

A) Dark matter exists today, whereas dark energy existed only until the strong nuclear force became a separate force at the Planck time.
B) Dark energy is the energy emitted by dark matter, much as luminous energy (light) is emitted by visible matter.
C) There is no difference: Energy has mass by E = mc², and dark matter and dark energy are two names for the same effect.
D) Dark matter is attractive and slows the universal expansion, whereas dark energy is repulsive and accelerates the universal expansion.