Which of the following best defines biological evolution within a population? Select one: a. change in allele frequencies over time b. natural selection c. survival of the fittest d. phenotypic change within an individual’s lifetime

a. change in allele frequencies over time

Explanation:

Biological evolution is defined as the genetic changes from generation to generation.

Biological evolution can also defined as the changes in the inherited traits in a population over successive generation of organisms. Changes in the allele frequencies over a time causes changes in the genetic expression of an organism, which is a key characteristics of biological evolution.

The genetic expression changes from generation to generation during reproduction process and hence different characteristics tend to exist within any given population and shows genetic variation.

Hence, the correct option is a. "change in allele frequencies over time".

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.