Which of the following denotes particles
in a liquid state?
a. particles are packed tightly together, allowing no
movement
b. particles are able to move freely, some friction occuring
c. particles are packed tightly together, allowing some
movement
d. particles are moving very fast

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).

he forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?