No two people are genetically identical, except for identical twins. the main source of genetic variation among humans is
a. new mutations that occurred in the preceding generation.
b. genetic drift.
c. the reshuffling of alleles in sexual reproduction.
d. environmental effects.

c. the reshuffling of alleles in sexual reproduction.

Explanation:

During gametogenesis, meiosis occurs in reproductive cells. As a result, haploid gametes are produced. During meiosis, a process called ‘crossing over’ occurs in the pachytene stage of prophase I of meiosis. During crossing the chromosome segments are exchanged between non-sister chromatids of homologous chromosomes. Exchange of chromosome segment creates a new combination of genes or genetic recombination and produces hybrids. Thus, genetic variation occurs in all sexually reproducing organisms due to crossing over.    

i'm gonna put a couple so you can chose from

explanation:

if you know the fur color of the offspring mice, you can use the ratios to identify the genotypes of the parents.

if either parent mouse passes a dominant allele, the offspring will have black fur.

if the parental mice has two different fur color (i.e white and black) , the color of the offspring's fur would be either black, white, or the combination of both (grey)

hope this : )

artificial selection

explanation:

this occur when man select base on their intelligent