**Core Concept**
The question pertains to the ionization potential of local anesthetics, which is a crucial determinant of their potency and efficacy. **Ionization potential** refers to the ability of a drug to exist in its ionized form, which is essential for crossing the neuronal membrane and exerting its anesthetic effect. Local anesthetics work by blocking **sodium channels**.

**Why the Correct Answer is Right**
The correct answer has the maximum ionization potential, meaning it has the highest percentage of ionized form at physiological pH. This is due to its **pKa value**, which is close to the physiological pH, resulting in a higher proportion of the ionized form. The ionized form of the local anesthetic is responsible for binding to **sodium channels** and preventing the initiation and transmission of nerve impulses.

**Why Each Wrong Option is Incorrect**
**Option A:** Has a lower ionization potential due to its higher pKa value, resulting in a lower proportion of the ionized form at physiological pH.
**Option B:** Has a lower ionization potential due to its lower pKa value, resulting in a lower proportion of the ionized form at physiological pH.
**Option C:** Has a lower ionization potential due to its chemical structure, which favors the non-ionized form.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that local anesthetics with higher ionization potential are more potent and have a faster onset of action. This is because the ionized form is more effective at binding to **sodium channels** and blocking nerve conduction.

**Correct Answer:** D. Lidocaine.