One codon codes for a start, the amino acid I and there are 3 that code for
stop or

answer; i believe that the correct answer is ; males are hemizygous for the x chromosome;

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).