**Core Concept**
The question is testing the pharmacokinetic properties of benzodiazepines, specifically their duration of action. Benzodiazepines are a class of sedative-hypnotic drugs that act on the central nervous system to produce anxiolytic, muscle relaxant, and hypnotic effects. Their duration of action is influenced by their elimination half-life, which is the time required for the plasma concentration of the drug to decrease by half.

**Why the Correct Answer is Right**
The shortest acting benzodiazepine is Triazolam, which has an ultra-short elimination half-life of approximately 1.5-5.5 hours. This allows for rapid termination of its effects, making it ideal for use as a hypnotic agent in the treatment of insomnia. Triazolam acts by enhancing the activity of the neurotransmitter gamma-aminobutyric acid (GABA) at the GABA_A receptor, leading to sedative and hypnotic effects.

**Why Each Wrong Option is Incorrect**
* **Option A:** Lorazepam has a longer elimination half-life of around 10-20 hours, making it a less suitable choice for short-acting effects.
* **Option B:** Midazolam has a rapid onset of action but a longer duration of action compared to Triazolam.
* **Option C:** Diazepam has a long elimination half-life and is primarily used for its anxiolytic and muscle relaxant effects.

**Clinical Pearl / High-Yield Fact**
When choosing a benzodiazepine, consider the duration of action and the specific indication. Ultrashort-acting benzodiazepines like Triazolam are ideal for hypnotic effects, while longer-acting agents like Diazepam are better suited for anxiolytic and muscle relaxant effects.

**Correct Answer: C. Triazolam**