Final answer:
The carboxylic ester among the given compounds is option c) CH₃CH₂COOCH₃, which features the distinctive ester functional group. The option (C) is correct.
Step-by-step explanation:
The compound that is a carboxylic ester among the given options is CH₃CH₂COOCH₃. Carboxylic esters are characterized by the presence of a carbonyl group (C=O) directly bonded to an oxygen atom that is further connected to an alkyl or aryl group.
The overall structure looks like RCOOR', where R and R' can be hydrocarbon chains or hydrogen. Option c) fits this description, with CH₃CH₂ as one part of the ester (the acyl group), and OCH₃ as the alkoxy component of the ester group. In comparison, option a) represents a carboxylic acid, b) an ether, and d) a ketone. Therefore, option (C) is correct.