Which type of ion channel is primarily responsible for repolarization after an action potential in neurons?

The repolarization phase of an action potential is largely mediated by potassium channels. After an action potential is generated, there is a rapid influx of sodium ions through voltage-gated sodium channels, which depolarizes the neuron. Following this depolarization, the sodium channels begin to inactivate, and the voltage-gated potassium channels open in response to the change in membrane potential.

As the potassium channels open, potassium ions flow out of the neuron due to both the concentration gradient and the electrochemical gradient. This efflux of positively charged potassium ions causes the interior of the neuron to become more negative, effectively repolarizing the cell back toward its resting membrane potential. This process is essential for returning the neuron to its baseline state after the excitatory influx of sodium ions.

In summary, potassium channels play a critical role in repolarization by allowing potassium ions to leave the cell, which restores the negative charge inside the neuron after the depolarization phase of an action potential. This is why the correct answer highlights potassium channels as the key players in this process.