Final answer:
If a hyperpolarizing graded potential and a depolarizing graded potential of similar magnitudes arrive at the trigger zone at the same time, they are most likely to cancel each other out.
Step-by-step explanation:
If a hyperpolarizing graded potential and a depolarizing graded potential of similar magnitudes arrive at the trigger zone at the same time, they are most likely to cancel each other out.
This is because the depolarizing graded potential will increase the membrane potential towards the threshold for an action potential, while the hyperpolarizing graded potential will decrease the membrane potential away from the threshold.
The net effect will be a cancellation of the two potentials, resulting in no action potential being fired off.