**Core Concept**
Methanol is a toxic alcohol that exerts its effects through the inhibition of mitochondrial enzymes, specifically cytochrome c oxidase (Complex IV) in the electron transport chain. This inhibition leads to a decrease in ATP production, resulting in cellular dysfunction and ultimately, organ failure.

**Why the Correct Answer is Right**
Methanol's toxic effects are primarily mediated by its metabolite, formic acid, which accumulates in the body after methanol is metabolized by alcohol dehydrogenase. Formic acid binds to the iron atom in cytochrome c oxidase, thereby inhibiting the enzyme's activity. This disruption in the electron transport chain causes a significant decrease in ATP production, leading to cellular energy crisis and organ failure.

**Why Each Wrong Option is Incorrect**
**Option A:** While methanol does have toxic effects, it is not primarily known for its effects on the nervous system.
**Option B:** Methanol does not primarily affect the renal system.
**Option C:** Methanol does not primarily affect the cardiovascular system.

**Clinical Pearl / High-Yield Fact**
Methanol poisoning is a classic example of a toxic alcohols, which can be difficult to diagnose due to the lack of specific symptoms. A key diagnostic clue is the presence of metabolic acidosis with a high anion gap, which is often accompanied by elevated lactate levels.

**Correct Answer: C. Visual system**