**Core Concept**
Fomepizole is a specific antidote used in the management of methanol and ethylene glycol poisoning. It works by inhibiting alcohol dehydrogenase, an enzyme responsible for the conversion of methanol to its toxic metabolites, formaldehyde and formic acid.

**Why the Correct Answer is Right**
Fomepizole competitively inhibits alcohol dehydrogenase, thereby preventing the formation of toxic metabolites. This action helps to reduce the severity of methanol poisoning and its associated symptoms, such as visual disturbances, nausea, and seizures. By blocking the enzyme, fomepizole allows the body to eliminate methanol without converting it to its toxic metabolites.

**Why Each Wrong Option is Incorrect**
**Option A:** Cannabis poisoning - Fomepizole is not used as an antidote for cannabis poisoning. Cannabinoid receptor antagonists or inverse agonists may be explored for treatment, but fomepizole is not indicated.

**Option B:** Cannabis poisoning - Fomepizole's mechanism of action is specific to alcohol dehydrogenase inhibition and is not relevant to cannabis poisoning.

**Option C:** Lead poisoning - Fomepizole is not used to treat lead poisoning. Chelating agents like succimer or penicillamine are typically used to remove lead from the body.

**Option D:** Cadmium Poisoning - Fomepizole is not used to treat cadmium poisoning. Chelating agents like penicillamine or British anti-Lewisite (BAL) may be used to remove cadmium from the body.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that fomepizole is a specific antidote for methanol and ethylene glycol poisoning, and its use should be considered in patients presenting with symptoms of these toxicities. Early administration of fomepizole can significantly reduce the severity of symptoms and improve patient outcomes.

**✓ Correct Answer: A. Methanol poisoning**