Earth’s rotation causes surface currents in the northern hemisphere to
a)
curve clockwise
b)
move in straight lines.
c)
curve counterclockwise.
d)
move in diagonal lines.

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).