Final answer:
The opening of voltage-gated sodium channels predominantly dictates the depolarization phase of an action potential in neurons.
Explanation:
Depolarization phase of an action potential in neurons is primarily dictated by the opening of voltage-gated sodium channels. When the cell's membrane potential reaches threshold, these channels open, allowing an influx of sodium ions that causes rapid depolarization. This depolarization continues as more sodium channels open, creating a wave of depolarization along the neuron.
Learn more about Action potentials here:
https://brainly.com/question/30634467
