Explain why a person with an allele for a particular trait may not have a phenotype that shows the trait.

This is because maybe that allele for the trait is recessive and the person is heterozygous. If the person is heterozygous, it means that they have both the dominant and recessive allele for a trait. This matches the requirements of having the allele for a particular trait but not showing the phenotype of that.

Explanation:

answer; i believe the correct answer is (secondary prevention);