**Core Concept**
The term "date rape drug" refers to substances that are used to facilitate sexual assault by rendering the victim unconscious or incapacitated. These drugs are often odorless, tasteless, and colorless, making them difficult to detect.

**Why the Correct Answer is Right**
GHB (gamma-hydroxybutyrate) is a central nervous system depressant that can cause sedation, amnesia, and loss of motor control. It is often used as a date rape drug because it can be administered in small amounts, often in beverages, and its effects can be rapid and unpredictable. GHB works by binding to GABA receptors in the brain, leading to a decrease in neuronal activity and an overall sedative effect.

**Why Each Wrong Option is Incorrect**
* **Option A:** Rohypnol, also known as flunitrazepam, is a benzodiazepine that can cause sedation and amnesia, but it is not as commonly associated with date rape as GHB.
* **Option B:** Ketamine is an anesthetic that can cause dissociative effects and sedation, but it is not typically used as a date rape drug.
* **Option D:** Alcohol is a depressant that can impair judgment and increase the risk of sexual assault, but it is not a specific date rape drug.

**Clinical Pearl / High-Yield Fact**
GHB can cause rapid and unpredictable effects, including loss of consciousness, amnesia, and respiratory depression. It is essential for healthcare providers to be aware of the potential use of GHB as a date rape drug and to consider it in the differential diagnosis of patients presenting with symptoms of sedation or amnesia.

**Correct Answer:** C. GHB.