Question

when the blood pressure of a vessel drops below the critical closing pressure for that vessel, multiple choice there is hypertension. there is an increase in blood flow. there is an increase in peripheral resistance. the vessel collapses. the vessel expands.

Explanation:

The critical closing pressure is the minimum pressure required to keep a blood - vessel open. When the blood pressure in a vessel drops below this value, the vessel collapses due to the lack of sufficient pressure to maintain its patency. Hypertension is high blood pressure, an increase in blood flow is not related to the vessel closing, an increase in peripheral resistance is not the direct result of blood pressure dropping below critical closing pressure, and the vessel does not expand when pressure drops below the critical closing pressure.

Answer:

the vessel collapses.