A(n) is a one-celled organism formed by the union of a sperm and an egg. a. zygote blastocyst an. embryo d. fetus

not the best question format lol but what i think might as scale color is controlled by a single gene with two alleles, the green allele and the yellow allele. when moths that are homozygous for green scales are mated with moths that are homozygous for yellow scales, 100% of the offspring have green scales.

b is the best answer for this question.