Clemmensen reduction is a chemical reaction used to convert a carbonyl compound, specifically a ketone or aldehyde, into an alkane. This reduction is carried out under acidic conditions using zinc amalgam (Zn-Hg) and hydrochloric acid (HCl) as the reagents.

The process involves several steps:

1. Formation of a complex: In the presence of HCl, the zinc amalgam (Zn-Hg) reacts with the carbonyl compound to form a complex. This complexation is an important step as it helps in the subsequent reduction process.

2. Reduction: The complex formed in the previous step undergoes reduction. The zinc in the Zn-Hg reagent acts as a reducing agent, donating electrons to the carbonyl compound. As a result, the carbonyl group is converted into a methylene group (-CH2-).

3. Acidic workup: Once the reduction is complete, the reaction mixture is treated with water or dilute acid to neutralize the acidic conditions. This step helps in the isolation of the reduced product.

The other options given in the question do not involve the necessary reagents for the Clemmensen reduction:

- Option A: Hydrogen gas (H2) and platinum (Pt) are commonly used in catalytic hydrogenation reactions, not in Clemmensen reduction.

- Option B: Glycol with KOH is used in the reaction known as the Williamson ether synthesis, which involves the formation of ethers, not the reduction of carbonyl compounds.

- Option D: Lithium aluminum hydride (LiAlH4) is a powerful reducing agent commonly used in organic synthesis, but it does not specifically perform Clemmensen reduction.

Therefore, the correct answer is option C, which involves the use of zinc amalgam (Zn-Hg) and hydrochloric acid (HCl) for the Clemmensen reduction of a ketone.