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

Fact 2: Population densities affect the balance of the environment.

Given the two facts above, answer the question "What do the average number of individuals per unit of area or volume affect?" with the following options: 
- that material's properties
 - our landscape
 - balance of the environment
 - death and devastation
 - important habitats
 - swamp vegetation
 - the environment
 - Animal survival


 

   balance of the environment      