DeShawn is studying homeostasis and circulation. To organize his findings, he constructs two models of the human heart, veins, and arteries: one to represent a non-smoker, and one that includes attributes typically found in a smoker. By comparing the two models, which relationship of cause and effect can DeShawn best explain?

Which of the following factors would not contribute to allopatric speciation? a) a population becomes geographically isolated from the parent population. b) the separated population is small, and genetic drift occurs. c) the isolated population is exposed to different selection pressures than the ancestral population. d) different mutations begin to distinguish the gene pools of the separated populations. e) gene flow between the two populations is extensive.