Answer:
Homeostasis
Step-by-step explanation:
Homeostasis describes the tendency of the body to maintain a "constant" internal state. If you get cold, your body responds by increasing processes that make you warmer (e.g. shivering) in an effort to restore things back to how they were. The same thing is happening here - blood pressure has gone down, so the body responds by doing things to increase blood pressure such as by increasing angiotensin II.