Plants depend on the atmosphere for the largest source of? 1.) phosphorus 2.)oxygen 3.)carbon 4.)water

true, i don't really know what you're asking but from the info you provided im guessing the answer is true.

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).