The answer is B: no
Hope this helps!
*Blood flow is regulated in all three types of blood vessels through constriction and dilation.
*Contraction of blood vessels slows blood flow, while relaxation of blood vessels, or dilation, allows free flow of blood.
*Muscle fibers control the constriction and dilation of vessels. In the capillaries, rings of muscle called capillary sphincters control blood flow.
*The directional flow of blood in the veins is controlled with valves , which prevent backward blood flow when closed, and allow blood to flow only toward the heart when open.
Vasoconstriction and vasodilatation allow blood vessels (arteries and veins) to control blood flow and thus control the blood pressure. This is possible because of the smooth muscle cells that surround the vessels. The contraction and dilatation of those muscles is controlled by chemical signals (e.g. norepinephrine constricts the vessels, while NO dilates them).
"Pathogens would invade the body and cause disease, such as giardia" is the one among the following choices given in the question that <span>describes how polluted water sources would most likely affect one’s personal health. The correct option among all the options that are given in the question is the last option or the fourth option.</span>
It is a perfect example of a natural selection.
(I'm not sure if this is the exact answer that you are looking for.)
