Which of the following serves as an actuating signal, or as part of an actuating signal, in a negative feedback system?
A. Action potentials in the fibers of the diaphragm muscle.
B. Action potentials in parasympathetic neurons that release acetylcholine (ACh) as their neurotransmitter and synapse upon skeletal muscles surrounding the arterioles.
C. Action potentials in peripheral hydrogen-ion-sensitive chemoreceptor neurons that release glutamate as their neurotransmitter from their central terminals located in the brain stem.