Answer:
Option 3. alkyne
Explanation:
The aldehydes are organic compounds with the functional group -CHO attached to parent chain it can be written as R-CHO where R is an alkyl group.
The alkenes are generally unsaturated hydrocarbon with a carbon to carbon double bond
(-C=C-) attached the parent chain.
The alkynes are unsaturated hydrocarbon with a carbon to carbon triple bond (-C≡C-) attached to the parent chain.
Alcohols are organic compounds with the functional group -OH attached to the parent chain. It can be written as R-OH where R is an alkyl group.
From the brief explanation above, the answer to the question is alkyne because the diagram has carbon to carbon triple bond (-C≡C-) attached to the parent chain.