I think the answer is "steroid."
Answer:
A) Elastin
Explanation:
Elastin is the principle load-bearing protien present in the wall of aorta. It is the protien which coil and recoils like a spring within the elastic fibres and accounts for elasticity of blood vessels. As during excerise , afterload is increased ,thus a stretch is produced in the vessels. Similarly im warm environment the vessels dilate this this stretch is produced by elastin.
Photosynthesis<span> makes the glucose that </span>cellular respiration<span> uses to make ATP</span>
Because each carbon is identical, they all have four valence electrons, so they can easily bond with other carbon atoms to form long chains or rings
