what does the notation rr mean to geneticists?\no heterozygous alleles\no homozygous alleles\no dominant…

Brief Explanations:

In genetics, alleles are alternative forms of a gene. When an organism has two different alleles for a gene (one dominant - represented by a capital letter and one recessive - represented by a lowercase letter like Rr), it is heterozygous. Homozygous alleles would be either RR or rr. Dominant alleles are only represented by capital letters (e.g., R), and recessive alleles by lowercase letters (e.g., r).

Answer:

heterozygous alleles