**Core Concept**
Akathisia is a movement disorder characterized by a subjective feeling of restlessness and an urge to move, often accompanied by fidgeting and agitation. It is a common side effect of antipsychotic medications, particularly the typical antipsychotics.

**Why the Correct Answer is Right**
The first-line treatment for akathisia involves the use of beta-blockers, which are effective in alleviating the symptoms of akathisia. Beta-blockers, such as propranolol, work by blocking the beta-adrenergic receptors in the brain, thereby reducing the sympathetic activity that contributes to the development of akathisia. This is because the symptoms of akathisia are thought to be mediated by an overactive sympathetic nervous system.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because anticholinergic medications, such as benztropine, are more commonly used to treat extrapyramidal side effects, such as parkinsonism and dystonia, rather than akathisia.
**Option B:** This option is incorrect because typical antipsychotics, such as haloperidol, are more likely to cause akathisia as a side effect rather than treat it.
**Option C:** This option is incorrect because benzodiazepines, such as clonazepam, may be used to treat akathisia in some cases, but they are not the preferred first-line treatment.

**Clinical Pearl / High-Yield Fact**
Beta-blockers are a safe and effective first-line treatment for akathisia, and they can be used in conjunction with other medications to manage symptoms.

**Correct Answer: D. Propranolol**