Identify the chemical structure of 1-propyn-1-ol.

1-propyn-1-ol is characterized by having a triple bond between the first and second carbon atoms and a hydroxyl (-OH) functional group attached to the same carbon as the triple bond. This specific arrangement is indicated by the name: "1-propyn-1-ol."

The structure you noted is CH₃-C≡C-OH, which features a carbon chain of three carbon atoms (prop) with a triple bond between the first and second carbons (indicated by the 'yne' suffix in propyn). The "1-ol" designation confirms that the hydroxyl group is attached to the first carbon of this chain, fulfilling the requirements established by the IUPAC naming conventions.

This structure is consistent with the molecular formula C₃H₄O and accurately represents the longest continuous carbon chain with the functional group positioned correctly. In contrast, the other choices do not align with the structural description of 1-propyn-1-ol, either featuring different types of bonds, misplacing the hydroxyl group, or not maintaining the correct carbon chain length.