The correct answer is A.
The reaction of cyclooctyne with HgSO4 in the presence of aqueous H2SO4 gives 1-octyne-1,6-dione. This is a Diels-Alder reaction, in which the two double bonds in cyclooctyne react with the sulfur dioxide molecule to form a six-membered ring. The sulfur dioxide molecule is activated by the HgSO4 catalyst, which makes it more reactive.
Option B is incorrect because it does not have the six-membered ring that is formed in the Diels-Alder reaction. Option C is incorrect because it has a different number of carbon atoms than cyclooctyne. Option D is incorrect because it has a different functional group than 1-octyne-1,6-dione.