The major effect of genetic drift is a) a reduction in genetic variability. b) a increase in genetic variation to accommodate changes in abiotic conditions. c) no change in population size but an increase in favorable alleles. d) a reduction in population size and an increase in genetic variability.

The correct answer would be A)a reduction in genetic variability.

Genetic drift refers to the random event by which the allele frequencies in a population get changed.

It is mainly caused by sampling error in selecting alleles to be passed on to the next generation.

It usually results in the loss of genetic variation due to the death of organisms which are carrying the variable alleles.  

It has major effects on the genetic variation when it is complemented with a bottleneck effect or founder effect.

a

Explanation:

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