**Core Concept**
Metoclopramide-induced dystonic reactions are a type of extrapyramidal side effect, which occur due to the blockade of dopamine receptors in the striatum. This leads to an imbalance in the dopaminergic and cholinergic neurotransmission, resulting in abnormal muscle movements.

**Why the Correct Answer is Right**
The drug used to treat metoclopramide-induced dystonic reactions is an anticholinergic medication. **Benztropine** works by blocking the action of acetylcholine at muscarinic receptors in the central nervous system, thereby counteracting the excessive cholinergic activity caused by dopamine receptor blockade. This leads to a reduction in dystonic symptoms.

**Why Each Wrong Option is Incorrect**
**Option A:** Haloperidol - This is an antipsychotic medication that blocks dopamine receptors, which would worsen the dystonic reaction.
**Option B:** Diazepam - While benzodiazepines can be used to treat anxiety and muscle spasms, they are not the primary treatment for metoclopramide-induced dystonia.
**Option C:** Metoclopramide - Re-administering the offending medication would only exacerbate the dystonic reaction.

**Clinical Pearl / High-Yield Fact**
In cases of metoclopramide-induced dystonia, it's essential to discontinue the medication and treat the patient with an anticholinergic agent, such as benztropine, to prevent further exacerbation of symptoms.

**Correct Answer:** C. Benztropine