Variable would be the most logical
Answer:
The answer is A.
Explanation:
The alerting system which is a part of the reticular activating system that provides the consciousness for us using the connections between the brain stem, cerebrum etc. consists of Locus Coeruleus which are nucleus located in the brain that responds to psychological stimuli such as panic, stress or discomfort. So the answer is A.
I hope this answer helps.
It can be observed and tested
