**Core Concept**
Atropine toxicity is a medical emergency that occurs when excessive amounts of the anticholinergic medication atropine are ingested or administered. This condition is characterized by the blockade of muscarinic acetylcholine receptors, leading to a range of systemic effects including tachycardia, dry mouth, blurred vision, and in severe cases, coma and death.

**Why the Correct Answer is Right**
The treatment of atropine toxicity involves the administration of physostigmine, an anticholinesterase inhibitor that can cross the blood-brain barrier. Physostigmine works by inhibiting the enzyme acetylcholinesterase, which breaks down acetylcholine into choline and acetic acid. By preventing the breakdown of acetylcholine, physostigmine increases the concentration of acetylcholine in the synaptic cleft, thereby overcoming the atropine-induced blockade of muscarinic receptors.

**Why Each Wrong Option is Incorrect**
* **Option A:** Gastric lavage would not be effective in treating atropine toxicity, as atropine is a lipid-soluble compound that can be absorbed from the gastrointestinal tract and distributed throughout the body.
* **Option B:** Activated charcoal may help to prevent the absorption of atropine, but it does not have a specific antidotal effect on atropine toxicity.
* **Option C:** Flumazenil is a benzodiazepine receptor antagonist that is used to treat benzodiazepine overdose, not atropine toxicity.

**Clinical Pearl / High-Yield Fact**
Physostigmine is a specific antidote for atropine toxicity because it can cross the blood-brain barrier and directly counteract the central effects of atropine, such as delirium and coma.

**Correct Answer:** D. Physostigmine