## Core Concept
Methyl alcohol (methanol) poisoning leads to a range of systemic effects, including central nervous system (CNS) depression, cardiac depression, and optic nerve atrophy. These effects are primarily due to the toxic metabolites of methanol.

## Why the Correct Answer is Right
The correct answer involves the metabolism of methanol. Methanol itself is not highly toxic; however, it is metabolized by **alcohol dehydrogenase** in the liver to **formaldehyde**, which is then rapidly converted to **formic acid** by **aldehyde dehydrogenase**. Formic acid is the primary toxic metabolite responsible for the adverse effects seen in methanol poisoning, including CNS depression, cardiac depression, and particularly, optic nerve atrophy. Formic acid disrupts cellular function and causes damage to the optic nerve, leading to visual disturbances and potentially permanent blindness.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because it does not accurately represent the mechanism by which methanol poisoning causes its effects.
- **Option B:** This option is incorrect as it does not specifically relate to the known toxic metabolites of methanol.
- **Option C:** While not directly provided, any option not directly implicating formic acid or the metabolic pathway of methanol would be incorrect for the reasons outlined above.

## Clinical Pearl / High-Yield Fact
A key clinical pearl in the management of methanol poisoning is the use of **fomepizole**, an inhibitor of alcohol dehydrogenase, which can be used as an antidote to prevent the formation of formic acid. Early treatment is crucial to prevent permanent damage, especially to the optic nerves.

## Correct Answer Line
**Correct Answer: D. Formic acid.**