Although the exact number of genes in human dna is unknown, scientists estimate the number to be around 20,000 to 25,000.
only one answer
which of the following is true about these genes?
a.)each human has completely different genes and alleles.
b.)there is only one variation, or allele, of each gene.
c.)there are several variations, or alleles, of many genes.
d.)each human has the exact same combination of alleles.

The correct answer is option C, There are several variations, or alleles, of many genes

Explanation:

In a given set of population, and for a given set of genes there can be a single allele or there can be multiple sets of allele. But since any individual can carry only set of chromosome per cell,an individual only carries one or two alleles per gene. But if there are several genes then there would be several variations, or alleles, of many gene

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