## Core Concept
Angel dust, also known by its chemical name **phencyclidine (PCP)**, is a dissociative anesthetic that has been used recreationally for its hallucinogenic and euphoric effects. It acts primarily by blocking **N-methyl-D-aspartate (NMDA) receptors** in the brain, which are involved in regulating the flow of ions and play a critical role in synaptic plasticity and memory.

## Why the Correct Answer is Right
The correct answer, **phencyclidine (PCP)**, is right because PCP is commonly referred to as angel dust due to its appearance as a white crystalline powder. It was initially developed as an anesthetic but due to its severe side effects, including hallucinations, dissociation, and potential for abuse, its medical use was discontinued. PCP's mechanism of action involves the blockade of **NMDA receptors**, which disrupts normal neurotransmission and leads to its psychoactive effects.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because it is not specified, making it impossible to assess its accuracy.
- **Option B:** This option is incorrect because it is not specified, making it impossible to assess its accuracy.
- **Option C:** This option is incorrect because it is not specified, making it impossible to assess its accuracy.

## Clinical Pearl / High-Yield Fact
A key point to remember is that **PCP (angel dust)** can cause a range of systemic effects, including **hypertension, tachycardia, and respiratory distress**, and its use can lead to **psychosis**, **seizures**, and **coma**. Clinicians should be aware of its potential for abuse and its challenging management in acute intoxication.

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