In which situation would a heterozygous genotype typically express a dominant trait?

A heterozygous genotype typically expresses a dominant trait in situations where one allele is dominant over the other. In genetics, alleles can be categorized as dominant or recessive. A dominant allele is one that will express its phenotype even in the presence of a different allele—meaning that if an individual has one dominant allele and one recessive allele (the heterozygous condition), the dominant trait will be observed.

This principle is grounded in Mendelian genetics, where dominant alleles mask the expression of recessive alleles in a heterozygous pairing. For example, if a dominant allele codes for a trait such as brown eyes and the recessive allele codes for blue eyes, an individual with one allele for brown eyes (dominant) and one for blue eyes (recessive) will exhibit brown eyes.

The other options, while related to genetic expression, do not correctly address the situation of expressing a dominant trait in a heterozygous genotype. A stable environment or occurrences of mutations can certainly affect traits and their expression but do not define the fundamental relationship of dominance and recessiveness between alleles. Additionally, situations where both alleles are equally expressed would indicate codominance, which is not applicable to the classic dominant-re