Which generation showed the greatest frequency of having one of each allele?

To answer your question accurately, it would be essential to have context about the specific genetic cross you're referring to. However, I can explain which generation generally shows the greatest frequency of heterozygosity (having one of each allele) by discussing a classic Mendelian monohybrid cross.

Assuming we're dealing with a simple Mendelian trait where there are two alleles (one dominant and one recessive), and we start with parents that are purebred for the given trait (one parent is homozygous dominant and the other is homozygous recessive), their offspring represent the F1 generation.

In a typical monohybrid cross, the parental (P) generation could consist of one individual with genotype AA (homozygous dominant) and another with genotype aa (homozygous recessive). The offspring (F1 generation) will all have the genotype Aa, meaning they carry one copy of each allele. In this case, the F1 generation will show the greatest frequency of heterozygosity, as all the members of this generation will have one of each allele.

If these F1 individuals are then crossed (an F1 cross), the offspring (the F2 generation) will exhibit a genetic ratio of 1:2:1 — one homozygous dominant (AA), two heterozygous (Aa), and one homozygous recessive (aa) — given a large enough sample size. Therefore, the F2 generation will have a lower frequency of heterozygotes compared to the F1 generation because only half of the F2 offspring (2 out of 4) will have one of each allele on average.