A: Because the environments and ecosystem show little change of time, the organisms that choose to adapt to different environments will migrate and become suited for new habitats.

B: Because the environments and ecosystems show little change over time, organisms are already adapted for surviving in their given habitats for which they are made.

C: As environments and ecosystems change over time, the gene pool also changes because organisms that have the best suited traits are more likely to survive and reproduce.

D: As environments and ecosystems change over time, the gene pool also changes because organisms must adapt to survive and those that acquire suitable traits are more likely to survive and reproduce.