I believe it is A (Adenine)
Answer:
Positive natural selection.
Explanation:
The positive natural selection is a type of natural selection that increases the frequency of an allele or trait when it is advantageous for the population. What happened in the example is that the mouth with the slight change in morphology (trait) was more advantageous for the population in the south in relation to the ancestral morphology (still preserved in the population in the north), and therefore its frequency increased. This, in turn, is due to the fact that the food (prey) is not the same in the two habitats (north and south). The specific prey in the south, caused the new morphology to be selected, (increasing the frequency of individuals with the new mouth), becasue probably that trait allows the trouts in the south to hunt more effectively.
Correct answer: A). Move away from one another
The divergent boundaries are formed when the tectonic plate move away from each other. It forms volcanic islands that occur when the plates move away in order to produce gaps that are filled by molten lava.
The divergent boundary contributes to the formation of seafloor spreading. When the plates that are made up of oceanic crust move away from each other, a crack in the ocean floor appears. Then the magma oozes out from the mantle to fill that crack that results in ocean ridges.
Hence, the correct answer would be option A.
