When propyne is treated with aqueous H2SO4 in the presence of HgSO4, the major product formed is acetone (option C). Let's understand the reaction and the mechanism involved.

1. Formation of the intermediate:
The first step involves the addition of H2SO4 to propyne, forming an intermediate. The acidic nature of H2SO4 protonates the alkyne (propyne) to form a more stable carbocation intermediate.

2. Formation of the carbocation:
The carbocation formed in the previous step undergoes rearrangement to form a more stable carbocation. The rearrangement involves a 1,2-hydride shift, where a hydrogen atom from the adjacent carbon shifts to the carbocation, resulting in the formation of a more stable tertiary carbocation.

3. Nucleophilic attack:
Water (H2O) acts as a nucleophile and attacks the carbocation, leading to the formation of a new carbon-oxygen bond. The nucleophilic attack occurs at the positively charged carbon atom of the carbocation, resulting in the formation of a new bond between the carbon and oxygen atoms.

4. Deprotonation:
The final step involves the deprotonation of the intermediate by the acidic conditions. In the presence of excess H2SO4, the intermediate is protonated by H2SO4 to give the final product, acetone.

Overall reaction:
Propyne + H2SO4 + HgSO4 → Acetone

The presence of HgSO4 in the reaction acts as a catalyst, facilitating the rearrangement of the carbocation intermediate.

In summary, when propyne is treated with aqueous H2SO4 in the presence of HgSO4, the reaction proceeds through the formation of a carbocation intermediate, which undergoes rearrangement and subsequent nucleophilic attack by water to give acetone as the major product.