Valves ensure blood flows toward your heart. Vein valves work to bring the blood that flowed down via arteries back up to your heart.
The correct answer is E:Endosperm
Theories are often the best explanations of natural phenomena we currently have. Yet, what one has to realize is that science is ever changing. That is why (B) is the correct answer, as new examinations, experiments, and discoveries could change some of these well-accepted theories. There is no way to "harm science" with viable observations and discoveries so (A) is incorrect. Answer (D) is also wrong since there is no assurance that a theory will never change in the future as they are merely accepted hypotheses. Answer (C) is not the best answer since theories are usually well supported and wouldn't be veritable if every examination proved flaws.
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Answer:
it is D because if the parasite feeds on blood not enough blood will make the hosts heart no pump enough blood and eventually die
Dehydration because no water is being permeated.
