Complete the Following Sentence: in the Condition Known as Population

Multiple Choice

Complete the following sentence: In the condition known as population inversion,

A) the amount of one type of gas atoms is larger than that of another in a mixture.
B) the number of energy levels that are populated is larger than that of unpopulated levels.
C) there are more electrons occupying lower energy levels than occupying higher energy levels.
D) there are more electrons occupying higher energy levels than occupying lower energy levels.
E) there are more photons than electrons in a given system.