What do scientists think the first organisms on Earth were?

answer; i believe its echoic memory,it is believed to last three to four seconds; good luck

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).

a. 35°c

b. 25°c

c. 10°c

d. 40°c