What concept explains how alleles can mask or influence the expression of other alleles?

The concept that explains how alleles can mask or influence the expression of other alleles is known as the Law of Dominance. This principle, first described by Gregor Mendel in his foundational work on inheritance patterns, states that in a heterozygous genotype (where two different alleles for a trait are present), one allele can dominate the other, determining the phenotype (the observable traits).

In cases of dominant and recessive alleles, the dominant allele will express its trait regardless of the presence of the recessive allele. For instance, if an individual has one dominant and one recessive allele for a specific trait, such as flower color, the dominant allele will manifest in the flower's color, while the recessive allele does not contribute to the observable trait. This concept is fundamental in understanding genetic inheritance and is crucial for predicting the characteristics of offspring based on their parental alleles.

The other options do not accurately capture this important genetic principle. The Law of Completeness and the Law of Interaction are not established concepts in classical genetics, and the Law of Distinction does not pertain to how alleles function in terms of dominance or recessiveness. Understanding the Law of Dominance helps clarify how specific traits are inherited and expressed in organisms.