What is the correct structure of acetone?

The correct structure of acetone is represented as CH₃-CO-CH₃. Acetone, or propan-2-one, is a simple ketone with a three-carbon chain where the carbonyl (C=O) group is situated between two methyl (CH₃) groups. This structure can be visualized as a central carbon atom that is double-bonded to an oxygen atom and single-bonded to two other carbon atoms, each of which is part of a methyl group.

This molecular arrangement corresponds to the functional group of a ketone, characterized by having the carbonyl group (C=O) flanked by carbon atoms. Therefore, the presence of the two methyl groups on either side of the carbonyl in the structure confirms it as acetone.

The other options present different structures that do not represent acetone. For example, one suggests an alkenyl connection, another implies a different alkyl arrangement, and one represents a carboxylic acid rather than a ketone. The clarity of acetone's structure as a simple ketone with the specific arrangement of its atoms supports the correctness of the answer chosen.