Select the correct answer from each drop-down menu. Neurons transmit signals to the central nervous system. The brain processes this information to initiate a response. Two neurons communicate with each other through the . The is released at the site to initiate action potential and carry the signal through the body.

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.