Fact 1: Population density is the average number of individuals per unit of area or volume.

Fact 2: Density is the population divided by the area.

Given the two facts above, answer the question "What is the average number of individuals per unit of area or volume?" with the following options: 
- population divided by class
 - population divided by area
 - solid, liquid, gas
 - biological diversity
 - competing for resources
 - population divided by income
 - population divided by wealth
 - Something that makes plants green


 

  population divided by area       