Answer: all of the above!
The second statement best explains the type of blood vessel and the function of these vessels' valves - <span>These are veins, which prevent the backflow of blood because the walls have little muscle to pump blood back to the heart.
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Veins are large blood vessels which carry blood back to the heart. <span>Veins have a system of valves to prevent back-flow.</span>
The real solution isn't banning them. People aren't the ones who dump them in to the oceans. Yet sometimes they do on beaches. The ones who dump them are corporate companies. We need to enforce laws saying that dumping is bad, and maybe a humongous fine like 10 billion, to scare away corporate dumpster companies away from the seaside
