Fact 1: Migration is a type of movement that changes population size.

Fact 2: Migration Much of the life of a spiny lobster involves travel.

Given the two facts above, answer the question "A life involving travel is a type of movement that changes what?" with the following options: 
- Continents drifting
 - the environment
 - Animal survival
 - important habitats
 - major threat to health
 - population size
 - an organism's body
 - Something to move


 

      population size   