Genetic variation . is created by the direct action of natural selectionb. must be present in a population before natural selection can act upon the populationc. arises in response to changes in the environmentd. tends to be reduced by when diploid organisms produce gametes

The correct answer is b. must be present in a population before natural selection can act upon the population

Explanation:

Genetic variation can be caused by mutation, recombination between chromosomes during meiosis and by fusion of two genetically different gametes during sexual reproduction.

This genetic variation is necessary for the evolution of any population. Natural selection acts on every individual and it decreases the frequency of those alleles that are not suited for the environment and increase the frequency of those alleles which helps the individual to survive in the changing environment.

Therefore genetic variation must be present in the population before natural selection act on the.

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