Answer;
-Evolution by natural selection
-The theory of evolution by natural selection states that organisms that are better suited for their environment will survive and reproduce, while those that are poorly suited for their environment will die off.
Step-by-step explanation;
-The theory of evolution encompasses the well established scientific view that organic life on our planet has changed over long periods of time and continues to change by a process known as natural selection.
-Natural selection is the phenomenon that some traits confer a reproductive advantage (fitness), resulting in (a statistical expectation of) that trait increasing in the population over time (evolution).