According to the graph, which renewable energy resource did the united states use most during 2007? a) biomass b) petroleum c) natural gas d) hydroelectric

i think that the answer is biomass

a

Explanation:

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).