<span>a. a substance that is naturally found in the brain</span>
It is stored as triglycerides.
<span>I believe the answer is: clownfish/anemone
Clownfish is very territorial in nature. So, when they hide within the anemone, the clownfish would prevent smaller fishes from eating the anemone. In return, the anemone would prevent the bigger fish from reaching the clownfish when they hide in it.</span>
