Answer:
II, III, IV, I
Explanation:
Blood pressure regulation is an example of negative feedback mechanism. When the blood pressure is low, sensor in the blood vessels called baroreceptors detect this and send a signal to the control center which is the hypothalamus.
The hypothalamus compares the current blood pressure with the normal and proceeds to send signals to the heart, as well as blood vessels and kidneys. The heart begins to beat faster, thereby increasing the heart rate and a a result, blood pressure goes back up to normal.
