What does the term "allele" refer to?

The term "allele" refers to a specific variant of a gene that occupies a particular position on a chromosome. Each individual has two alleles for each gene, one inherited from each parent. This means that option B, which describes an allele as a duplicate of a specific gene, captures the idea that alleles are variations of the same gene that can produce different traits.

Alleles can differ in their sequence of nucleotides and can lead to variations in the physical expression of a trait, such as flower color in plants or blood type in humans. This concept is fundamental to genetics, as the variation among alleles contributes to the diversity we observe in many biological characteristics.