What is the major function of the valves found in human veins?

not only is it colder, it also becomes darker, less salty, and more dense.

kelp are large brown algae that live in cool, relatively shallow waters close to the shore. they grow in dense groupings much like a forest on land. these underwater towers of kelp provide food and shelter for thousands of fish, invertebrates, and marine mammal species.

e) all of the above