Which term reflects the relative number of each allele in a population?

The term that accurately reflects the relative number of each allele in a population is indeed allele frequency. Allele frequency refers to how common an allele is in a population, expressed as a fraction or percentage of all alleles at a particular locus in that population. This measurement is crucial for understanding genetic variation and evolutionary dynamics within populations.

In this context, other terms such as genotype frequency and phenotypic ratio do not measure the occurrence of individual alleles. Genotype frequency describes how often certain genotypes occur within a population, while phenotypic ratio relates to the observable traits and their proportions. Genetic diversity, meanwhile, encompasses the variety of genetic characteristics within a species, but does not specifically address allele counts or proportions. Therefore, allele frequency is the correct term to describe the relative abundance of alleles in a population.