Copper is a much better thermal conductor than glass. Which of the following is the only accurate explanation for this?

A. In glass, there are free electrons between the atoms that block the transfer of energy.

B. In copper, there are free electrons between the atoms that can transfer energy quickly through the material.

C. In copper the atoms vibrate more quickly than they do in glass.

D. In copper, the atoms are closer together than they are in glass.