The correct answer is alleles. Alleles are alternative forms or variations of a gene that occupy the same position on a specific chromosome. They determine the different traits or characteristics (phenotypes) that an organism can exhibit. Alleles can be dominant, where they are expressed and mask the presence of other alleles, or recessive, where they are only expressed if there are two copies present. To determine the different forms of alleles for a particular gene, we can study genetics through techniques such as DNA sequencing or genetic crosses.
