**Core Concept**
Metoclopramide is a prokinetic agent primarily used to enhance gastrointestinal motility. It works by blocking dopamine receptors in the gastrointestinal tract, which leads to increased acetylcholine release and enhanced gut motility. However, its action on central dopamine receptors can cause extrapyramidal side effects.

**Why the Correct Answer is Right**
Metoclopramide is known to cross the blood-brain barrier and act on central dopamine receptors, particularly D2 receptors. This action is responsible for its prokinetic effects in the gut but also leads to extrapyramidal side effects, such as dystonia, akathisia, and parkinsonism, due to its anticholinergic and antihistaminic properties. The drug's impact on central dopamine receptors is a significant factor in its side effect profile.

**Why Each Wrong Option is Incorrect**
**Option A:** Cisapride is another prokinetic agent, but it primarily acts by inhibiting the 5-HT4 receptor, which increases acetylcholine release and enhances gut motility. It does not have a significant impact on central dopamine receptors and therefore does not cause extrapyramidal side effects.

**Option B:** Domperidone is a prokinetic agent that primarily acts peripherally by blocking dopamine receptors in the gastrointestinal tract. Since it does not cross the blood-brain barrier, it does not have a significant impact on central dopamine receptors and therefore does not cause extrapyramidal side effects.

**Option C:** Ondansetron is an antiemetic agent that primarily acts by blocking 5-HT3 receptors. It does not have a significant impact on dopamine receptors and is not associated with extrapyramidal side effects.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the risk of extrapyramidal side effects with metoclopramide is higher in patients who are elderly, have a history of neurological disorders, or are taking other medications that affect the central nervous system.

**✓ Correct Answer: D. Metoclopramide**