Photosynthesis does not occur in deep water because O The water temperature is too cold O There is no sunlight.
O There are not enough nutrients
O The salinity level of the water is too high​

The salinity level is too high

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).