D, the black squirrels have survived because black has provided them with an advantage in this environment.
Survival of the fittest is talking about when you have traits that will help you, you are more likely to live rather than not having those traits. For example, a bird that swims a lot has webbed feet so it has a better chance of surviving then a bird who does not have webbed feet
The myelin sheath (C) insulates the axons.
The myelin sheath is a fatty substance, hence why it is great for insulation. <span />
Answer:
Stomach, small intestine, and pancreas
Explanation:
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