Bioremediation includes
the use of prokaryotes that can fix nitrogen
the use of prokaryotes to clean up pollutants
the use of prokaryotes as natural fertilizers
all of the above

the use of prokaryotes to clean up pollutants

Explanation:

Bioremediation, also called biological remediation, is a technique used to minimize the environmental impacts caused by pollution.

In this process biological degrading agents are used, particularly microorganisms (bacteria, fungi, yeast, enzymes, etc.), which detoxify areas contaminated by pollution. That is, we can say that bioremediation includes the use of prokaryotes to clean pollutants.

In bioremediation, prokaryotes remove or neutralize various toxic pollutants (organic and inorganic) from the environment, which are present in soils, waters (surface or underground), among others.

The microorganism used in the biological remediation process metabolizes and digests the contaminant. Consequently, it releases carbon dioxide (CO2) and water (H2O). A notorious example where bioremediation can be used is in the contamination (of soils or water resources) by petroleum and its derivatives.

the correct answer is:

a population changes in response to a change in the environment.