What is the powerhouse of the cell?

Mitochondria

Explanation:

Mitochondria play host to one of the most important processes in your body, called cellular respiration. Taking in glucose and oxygen, mitochondria produce energy, which they capture and package as energy-rich molecules of ATP.

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).