You didn't put any answer choices, but air and water are generally the greatest.
Answer:
<em>Geographic isolation</em>
Explanation:
Geographic isolation can be described as a term that describes the model of speciation in which a biological population becomes isolated from other members of the population and can no longer have gene flow with them.
The same scenario of gene isolation is occurring in the species of taods which live at the top of the mountains in southern Arizona. This population has become reproductively isolated fro all other species of toads within the mountain range.
A target cell respond to a hormone because it bears receptors
