Given question is incomplete. Complete question has been attached.
Answer:
C. Excessive potassium has diffused out causing hyperpolarization.
Explanation:
The nerve action potential can be divided into following stages:
- Stimulus is detected by the cell in resting stage.
- Sodium channels in the membrane open from where influx of sodium ions occur which is called depolarization
- After a while, sodium channels close and potassium channels open from where efflux of potassium ions occur which is called repolarization.
- The membrane potential further lowers due to continous efflux of potassium ions which is called hyperpolarization.
- After a while potassium channels close and membrane returns to its resting stage.
In the given figure, stage 4 depicts hyperpolarization because the membrane potential has dropped to the lowest point below -70mV. Hence, option C is correct.
