Answer:
The correct option is A. a second action potential is generated until the interval reaches the absolute refractory period.
Explanation:
The inter-stimulus interval (ISI) is the temporal interval between two successive stimuli, measured from the offset of the first stimulus to the commencement of the second.
A cell's refractory period is the time during which it is unable to replicate an action potential. Therefore, the absolute refractory period is the amount of time it takes for a second action potential to be initiated, regardless of how large a stimulus is applied repeatedly.
A second action potential is generated when the gap between the stimuli decreases until the interval reaches the absolute refractory period.
Therefore, the correct option is A. a second action potential is generated until the interval reaches the absolute refractory period.
That is, when the interval between the stimuli decreases, <u>a second action potential is generated until the interval reaches the absolute refractory period</u>.
