Answer: common descent
Explanation:
The theory of common descent suggests that the organisms which are found today has been evolved from the organisms used to live in the past. It is a scientific theory which explains the fact that all living organisms that are found on earth are the descendants of a single common ancestor that is the primitive organism. This has been confirmed by analyzing the features present in the fossil remains of the primitive organisms which are found to be nearly similar to that of the organisms living today.
