Which blood vessels connect the two sides of the vascular system?.

Choice B rationale:

The bronchioles are part of the airway that leads to the alveoli, but gas exchange does not occur here.

Choice C rationale:

The bronchus is a larger airway that leads to the bronchioles and then to the alveoli, but gas exchange does not occur here.

Choice D rationale:

While the lungs contain the alveoli where gas exchange occurs, saying that gas exchange occurs in the lungs is not as precise as saying it occurs in the alveoli.

The correct answer is Choice D.

Choice A rationale:

Vasoconstriction refers to the narrowing of blood vessels. When blood vessels constrict, they reduce the volume of blood that can flow through them, which increases the pressure. However, the flow is decreased, not increased.

Choice B rationale:

As explained above, vasoconstriction increases pressure but decreases flow.

Choice C rationale:

While vasoconstriction does increase pressure, it does not increase flow. Instead, it decreases flow.

Choice D rationale:

Vasoconstriction results in increased pressure and decreased flow. This happens because the narrowing of the blood vessels increases the resistance to blood flow, thereby increasing the pressure. At the same time, the reduced diameter of the blood vessels decreases the amount of blood that can flow through them.