Where is the location of the popliteal artery within the body?

This is because ventricular systole is the phase of the cardiac cycle when the ventricles contract and pump blood into the arteries.
The blood pressure in the arteries is greatest during this phase because of the forceful ejection of blood.
Choice B.
Atrial diastole is wrong because atrial diastole is the phase of the cardiac cycle when the atria relax and fill with blood from the veins.
The blood pressure in the arteries is lowest during this phase because the ventricles are also relaxed and not pumping blood.
Choice C.
Ventricular diastole is wrong because ventricular diastole is the phase of the cardiac cycle when the ventricles relax and fill with blood from the atria.
The blood pressure in the arteries is low during this phase because the ventricles are not pumping blood.
Choice D.
Atrial systole is wrong because atrial systole is the phase of the cardiac cycle when the atria contract and push blood into the ventricles.
The blood pressure in the arteries is not affected by this phase because the ventricles are still relaxed and not pumping blood.
The normal range for systolic blood pressure is less than 120 mm Hg and for diastolic blood pressure is less than 80 mm Hg.

Uterine contractions during childbirth illustrate a positive feedback mechanism.

A positive feedback mechanism is a process in which the end products of an action cause more of that action to occur in a feedback loop.
This amplifies the original action.
For example, when a woman goes into labor, the pressure of the baby’s head on the cervix stimulates nerve impulses that travel to the brain and trigger the release of oxytocin, a hormone that causes the uterus to contract.
The contractions increase the pressure on the cervix, which stimulates more nerve impulses, more oxytocin, and more contractions.
This cycle continues until the baby is delivered.
Choice A is wrong because body temperature control is an example of a negative feedback mechanism, which is when the end results of an action inhibit that action from continuing to occur.
For example, when the body temperature rises above normal, the skin sweats, and blood vessels dilate to release heat.
This lowers the body temperature back to normal and stops sweating and dilation.

Choice B is wrong because control of blood sugar is also an example of a negative feedback mechanism.
For example, when the blood sugar level rises after a meal, the pancreas secretes insulin, a hormone that helps cells take up glucose from the blood.
This lowers the blood sugar level back to normal and stops the insulin secretion.
Choice D is wrong because maintaining blood pressure is another example of a negative feedback mechanism.
For example, when the blood pressure drops due to blood loss or dehydration, the heart beats faster and stronger, and the blood vessels constrict to increase the blood pressure.
This restores the blood pressure back to normal and stops the heart rate and vessel constriction.