The correct answer is Variation.

Explanation:

The various traits or behaviours of an organisms are seen to have evolved over many years through natural selection, with the main aim of surviving in the environment. Natural variation is the process in which individuals are better adapted in the environment, with the main aim of surviving and reproducing. Variations, often down the genetic level, or caused by genetic mutation, often allows some members of a species to be better adapted to an environment. This also helps in the process of evolution, thus initiating natural selection and initiating force of natural selection.

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