Answer:
A change in a population over time
Step-by-step explanation:
Evolution can be described as the changes which occur in a population over time. The theory of evolution is based on natural selection. According to natural selection, those organisms which are better adapted to live in an environment live and pass on their characteristics to their offsprings. With the passage of time, those individuals are able to survive which are best adapted to survive in the changes which take place in an environment.