Answer the following question given this paragraph: 

Communities are made up of populations of different species. In biology, a population is a group of organisms of the same species that live in the same area. The population is the unit of natural selection and evolution. How large a population is and how fast it is growing are often used as measures of its health.


Q: What do you call a group of organisms of the same species that live in the same area?

 Choices:

- system

- ecosystem

- biosphere

- population

A:
population
