The compound resistant to oxidation is

t-Butanol

The correct answer is Option (2) → t-Butanol

Alcohol oxidation depends on the presence of $α$-hydrogen (hydrogen attached to the carbon bearing the OH group). Alcohols lacking $α$-hydrogen are resistant to oxidation.

Explanation

Option 1: Carbonic acid

Carbonic acid is not an alcohol and is already in a highly oxidized state. It exists in equilibrium with $CO_2$ and water and does not participate in typical oxidation reactions of alcohols.

Option 2: t-Butanol

t-Butanol is a tertiary alcohol. The carbon attached to the -OH group has no a-hydrogen. Since oxidation requires removal of this hydrogen, tertiary alcohols do not undergo oxidation under normal conditions, making them resistant.

Option 3: Ethyl alcohol

Ethyl alcohol is a primary alcohol and contains a-hydrogen. It readily undergoes oxidation to form aldehydes and further to carboxylic acids.

Option 4: Methyl alcohol

Methyl alcohol is also a primary alcohol and contains a-hydrogen. It can be oxidized to formaldehyde and further to formic acid.