If this is the picture you are talking about, the right answer is non-disjunction
Non-disjunction is the non-separation of homologous chromosomes at the time of cell division which results in the formation of ova or spermatozoa leading to an abnormality in the number of chromosomes of the egg thus fertilized by the spermatozoa.
The fertilized egg consists of either a single chromosome, what is called monosomy, or, conversely, three chromosomes, this is called trisomy. While naturally, the fertilized egg has a single pair of chromosomes.
Bacteria produce restriction endonucleases, or restriction enzymes, that recognize and cut up foreign DNA, including certain phage DNA.
Answer:
The variation might occur in the population that leads to the evolution of the species. This variation may occur due to natural selection, mutation or recombination.
The variation might change the genotype and allelic frequency of the population and might also change the phenotype of the individual in the population. The breeding adults of the left mouthed in 1981, 1987 and 1990 shows variation and was equally opposite phenotype which is more common in the population.