Answer: D
I hope this helps and have a great night !
<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>
The rungs are composed of hydrogen bonded paired Nitrogenous Bases. These pairings are Adenine to Thymine and Guanine to Cytosine.
Answer:
<h2> I don't know but my Answer is </h2><h3>from different environments ,each structure suits their environment better than the other's</h3>
