**Core Concept**
Benzodiazepines are a class of anxiolytic medications that modulate the activity of the central nervous system. Their mechanism of action primarily involves the enhancement of inhibitory neurotransmission through the GABA (gamma-aminobutyric acid) receptor complex.

**Why the Correct Answer is Right**
The correct answer is that benzodiazepines do not have GABA mimetic action. Instead, they act as allosteric modulators of the GABA_A receptor, a ligand-gated chloride channel. This means that benzodiazepines bind to a distinct site on the GABA_A receptor, increasing the frequency of chloride channel opening without directly activating the receptor. This action enhances the inhibitory effects of GABA, leading to sedative, anxiolytic, and anticonvulsant effects.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is true. Benzodiazepines do act on the midbrain, ascending reticular formation, and limbic system, contributing to their anxiolytic and sedative effects.

**Option B:** This statement is true. Benzodiazepines exert their effects through the GABA_A receptors, which are a type of ligand-gated chloride channel.

**Option C:** This statement is true. Benzodiazepines increase the conductance of Cl- channels by enhancing the activity of the GABA_A receptor.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that benzodiazepines are not GABA agonists, but rather GABA receptor modulators. This distinction is important for understanding their mechanism of action and for avoiding confusion with other classes of anxiolytic medications, such as barbiturates, which do have GABA mimetic action.

**✓ Correct Answer: D. It has GABA mimetic action**