## Core Concept
Anticholinergic drugs, also known as antimuscarinics, are substances that block the action of acetylcholine at muscarinic receptors in the central and the peripheral nervous system. These receptors are involved in various physiological functions, including smooth muscle contraction, heart rate modulation, glandular secretion, and cognitive functions.

## Why the Correct Answer is Right
is known for its anticholinergic properties, commonly used for its antihistaminic and sedative effects but also exhibits significant anticholinergic activity. and are well-recognized for their anticholinergic side effects, used in treating conditions like overactive bladder and COPD. On the other hand, primarily acts as a β2-adrenergic agonist, used in the treatment of asthma and COPD, and does not have significant anticholinergic properties.

## Why Each Wrong Option is Incorrect
* **Option A:** does have anticholinergic properties.
* **Option B:** is known for its anticholinergic effects.
* **Option C:** also exhibits anticholinergic activity.

## Clinical Pearl / High-Yield Fact
A key clinical point to remember is that anticholinergic side effects can be significant, including dry mouth, blurred vision, urinary retention, constipation, and in severe cases, confusion and delirium, particularly in the elderly.

## Correct Answer Line
**Correct Answer: D.**