**Core Concept**
Antipsychotics can cause hypotension due to their effects on the autonomic nervous system, particularly alpha-adrenergic blockade. This leads to vasodilation, decreased peripheral resistance, and a subsequent drop in blood pressure.

**Why the Correct Answer is Right**
The correct answer is **Haloperidol** due to its potent alpha-1 adrenergic receptor blockade. Haloperidid's potent blockade of alpha-1 receptors results in significant vasodilation, particularly in the arterioles of the skin and skeletal muscle, leading to a marked decrease in blood pressure. This effect is more pronounced than other antipsychotics, making Haloperidol the correct answer.

**Why Each Wrong Option is Incorrect**
**Option A:** Risperidone is an atypical antipsychotic with minimal alpha-1 adrenergic blockade, making it less likely to cause significant hypotension.

**Option B:** Quetiapine is an atypical antipsychotic that primarily blocks serotonin receptors, leading to minimal effects on blood pressure.

**Option C:** Clozapine is an atypical antipsychotic with a strong affinity for serotonin receptors, but minimal alpha-1 adrenergic blockade, making it less likely to cause significant hypotension.

**Clinical Pearl / High-Yield Fact**
When initiating antipsychotic therapy, monitor patients closely for orthostatic hypotension, particularly in the elderly or those with pre-existing cardiovascular disease.

**Correct Answer:** C. Haloperidol