Butanone is a four-carbon compound with the functional group
(c) ketone
Explanation for the correct options: Butanone is a four-carbon compound with the functional group ketone (-C=O).
Therefore, the given option (c) is correct.
Explanation for the incorrect options: Option (a): A carboxylic acid is an organic acid that contains a carboxyl group (COOH) attached to an R-group. Therefore it is incorrect.
Option (b): Aldehyde is an organic compound that contains (CHO) to an R - Group. Therefore it is incorrect.
Option (d): Alcohol is an organic compound that contains (R - OH ). Therefore it is incorrect.