## **Core Concept**
Drug-induced parkinsonism is a condition caused by certain medications that block dopamine receptors or deplete dopamine in the brain, leading to symptoms similar to Parkinson's disease. The management involves discontinuing the offending drug and using medications that can alleviate symptoms. **Anticholinergics** are often used to treat drug-induced parkinsonism.

## **Why the Correct Answer is Right**
The correct answer, **B. Trihexyphenidyl**, is an anticholinergic medication. Anticholinergics are considered the drug of choice for treating drug-induced parkinsonism because they can effectively counteract the extrapyramidal symptoms caused by dopamine receptor blockade. Trihexyphenidyl is a commonly used anticholinergic that works by correcting the imbalance between dopamine and acetylcholine in the basal ganglia.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is blank and does not provide a valid choice.
- **Option C:** This option is also blank and does not provide a valid choice.
- **Option D:** This option is blank as well and does not offer a valid medication for consideration.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that anticholinergics like **Trihexyphenidyl** are specifically useful for drug-induced parkinsonism but have limited efficacy in Parkinson's disease itself. Also, be cautious of the side effects of anticholinergics, especially in the elderly, such as dry mouth, blurred vision, constipation, and urinary retention.

## **Correct Answer Line**
**Correct Answer: B. Trihexyphenidyl**