I believe the answer is a
They use a internal pouch which is named swim bladder.
Explanation; Oxygen will enter a fish’s mouth, and passes through their gills. The oxygen will be taken and gets carried by hemoglobin through their bloodstream. Hemoglobin will take out some of the oxygen into their swim bladder. The amount of oxygen will show if they will sink or rise. Your question is how do they rise. If he goes up too much, the meaning of this is when the gas diffuses into their blood and out the gills.
Got this from a writing, but rephrased it.
B.
Humans are also part of ecosystems and if they cease to exist, human well being will be affected.
<span>The ventricles are the part of the heart that are responsible for the pumping action to move blood throughout the body. Therefore, the muscles in the ventricles are much larger and thicker to do their job properly. The atrium only has to pump blood through an open valve (the tricuspid valve) into the right ventricle. There is much less resistance to this flow of blood so much less muscle is needed. </span>
<span>Everyone’s DNA are different because they are different
people. One part of DNA are your genes. The genes are what you look like, hair
color, eye color, everything that you can
get from your parents. Even if you have a twin, it’s not necessary that you two
would have the same genes. For example, one could have green eyes and the other
could have brown eyes.
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<span>Good luck and hope I helped. :)</span>
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