**Core Concept**
Postural hypotension, also known as orthostatic hypotension, is a sudden drop in blood pressure when standing up from a sitting or lying position. This condition can lead to recurrent falls in elderly patients, making it a significant concern for geriatric patients. The underlying mechanism involves a failure of the autonomic nervous system to adequately regulate blood pressure in response to changes in posture.

**Why the Correct Answer is Right**
The correct answer is an anticholinergic medication, which works by inhibiting the action of acetylcholine at muscarinic receptors in the autonomic nervous system. Anticholinergic agents can cause a decrease in parasympathetic tone, leading to a decrease in blood vessel diameter and a subsequent decrease in blood pressure. This makes them a potential cause of postural hypotension, particularly in elderly patients who may already have compromised autonomic function.

• **Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the question, as it does not directly relate to postural hypotension or the autonomic nervous system.
**Option B:** This option is incorrect because, while certain medications can cause hypotension, they are not typically associated with postural hypotension in the same way as anticholinergic agents.
**Option C:** This option is incorrect because it is not a medication that is commonly associated with postural hypotension.

**Clinical Pearl / High-Yield Fact**
Anticholinergic medications can also cause other symptoms such as dry mouth, constipation, and urinary retention, which can be particularly problematic in elderly patients. It's essential to carefully evaluate the potential side effects of medications in this population.

**Correct Answer:** A.