They don't swell because of osmosis.
<span>The answer is C. In the event of someone having a stroke, it is necessary to control and stop the bleeding in the brain. Thinning the blood is necessary in cases of cardiovascular arrest because this will help avoid further blood clots forming. </span>
blood flows at a high pressure, so if the arteries are thin and less muscular, the arteries can explode due to the pressure. so it needs thick and muscular properties so that it can withstand the increasing pressure of the flow of blood.
im not sure why it needs to be elastic. Hope it helped :)