Which One of the Following Statements Concerning Electron Energy Bands

Multiple Choice

Which one of the following statements concerning electron energy bands in solids is true?

A) the bands occur as a direct consequence of the Fermi-Dirac distribution function
B) electrical conduction arises from the motion of electrons in completely filled bands
C) within a given band, all electron energy levels are equal to each other
D) an insulator has a large energy separation between the highest filled band and the lowest empty band
E) only insulators have energy bands