**Core Concept**
Benzodiazepines are a class of medications used to treat anxiety, insomnia, seizures, and muscle spasms. They work by enhancing the effect of the neurotransmitter gamma-aminobutyric acid (GABA) at the GABA_A receptor, leading to sedative, hypnotic, anxiolytic, anticonvulsant, and muscle relaxant properties.

**Why the Correct Answer is Right**
The shortest acting benzodiazepine is Triazolam. It has a rapid onset of action, with peak effects occurring within 30 minutes. This is due to its high lipid solubility, which allows it to quickly cross the blood-brain barrier. Triazolam is often used for the short-term treatment of insomnia, as it has a half-life of approximately 1.5-5.5 hours, which is shorter than most other benzodiazepines.

**Why Each Wrong Option is Incorrect**
**Option A:** Midazolam is incorrect because, although it is a short-acting benzodiazepine, it is primarily used for its anxiolytic and sedative effects in medical procedures, rather than for insomnia.
**Option B:** Lorazepam is incorrect because, while it is a short-acting benzodiazepine, it has a longer half-life than Triazolam, typically ranging from 10-20 hours.
**Option C:** Clonazepam is incorrect because it is a long-acting benzodiazepine, often used to treat seizures and anxiety disorders, but not typically for insomnia.

**Clinical Pearl / High-Yield Fact**
It's essential to note that benzodiazepines can be habit-forming, and their use should be limited to short-term treatment of insomnia. The risk of dependence increases with longer treatment durations and higher doses.

**Correct Answer:** C. Triazolam