Answer:
Nerve impulse
Explanation:
A nerve impulse is transmitted through the synaptic cleft by acetylcholine. When an impulse reaches the synaptic knob, it stimulates the vesicles to move towards the presynaptic membrane releasing the acetylcholine. The transmitter substance makes the membrane permeable. An action potential is then formed along the neuron.
C) Both members of the relationship
Answer:
I'm thinking maybe B, illustrates the principle of natural selection.
Explanation:
This example shows that, once a particular event happens in a species' ecosystem that negatively affects their lifestyle, natural selection occurs and kills off those with a disadvantageous adaptation (in this case the narrow-beaked finches, since they could no longer eat insects but did not have the beak size to crack seeds), allowing those with the advantageous adaptation (in this case, the thicker-beaked birds) to prosper.