**Core Concept**
Excitatory postsynaptic potentials (EPSPs) are a type of synaptic potential that occurs when a neurotransmitter binds to its receptor on the postsynaptic neuron, leading to an increase in the likelihood of action potential generation. This process is mediated by the opening of voltage-gated sodium channels, allowing positively charged ions to flow into the cell.

**Why the Correct Answer is Right**
When a neurotransmitter binds to its receptor on the postsynaptic neuron, it triggers a conformational change that exposes the binding site of the receptor to the surrounding extracellular fluid. This exposes the binding site to the neurotransmitter, allowing it to bind and trigger a series of downstream effects. In the case of an EPSP, the binding of the neurotransmitter causes the opening of voltage-gated sodium channels, allowing positively charged sodium ions to flow into the cell. This influx of positively charged ions depolarizes the postsynaptic neuron, increasing the likelihood of an action potential. The sodium channels are activated by the binding of the neurotransmitter to its receptor, which is typically a ligand-gated ion channel.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided, so we cannot evaluate its correctness.
* **Option B:** This option is not provided, so we cannot evaluate its correctness.
* **Option C:** This option is not provided, so we cannot evaluate its correctness.
* **Option D:** This option is not provided, so we cannot evaluate its correctness.

**Clinical Pearl / High-Yield Fact**
One key point to remember is that EPSPs are a type of synaptic potential that can be either excitatory or inhibitory, depending on the type of neurotransmitter and receptor involved. Inhibitory postsynaptic potentials (IPSPs) occur when a neurotransmitter binds to its receptor on the postsynaptic neuron, leading to an increase in the likelihood of chloride ions flowing into the cell, which hyperpolarizes the neuron.

**Correct Answer:** D.