A Solid Is an Insulator If

Multiple Choice

A solid is an insulator if:

A) Enough electrons are present to fill a band completely and the energy gap before the next empty band is small.
B) Enough electrons are present to fill a band completely and the energy gap before the next empty band is equal to or less than zero.
C) Enough electrons are present to fill a band completely and the energy gap before the next empty band is large.