Answer:
C. The opening of sodium channels
Explanation:
An Excitatory Post-Synaptic Potential (EPSP) is caused by the opening of sodium channels. When these channels open, positively charged sodium ions (Na⁺) flow into the neuron, causing a depolarization of the membrane potential. This depolarization makes the neuron more likely to fire an action potential, thereby contributing to excitatory signaling.
