Genetic mutation, crossing over during meiosis, polyploidy is an example of a cause of natural variation to the mechanism of natural selection. Thus, option A is correct.
What is natural variation?
The difference between cells, individual organisms or multiple organisms of any group or species caused either by climate change or genetic change on the expression of the genetic potential.
Variation shown in many ways such as physical appearance, metabolism, reproduction, fertility behavior, learning and mental ability, such variation is called as natural variation.
Therefore, in the above question we can say that all the example are best for natural variation. Thus, option A is correct.
Learn more about natural variation here:
https://brainly.com/question/1398553
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