Identify the functional group(s) of carboxylic acids (R represents any type of carbon chain):
Carboxylic acids are organic compounds that contain a carboxyl group (RCOOH, a carbon single bonded to a hydroxyl group and double bonded to an oxygen atom). Option C satisfies this definition. Option A and B are the functional groups for aldehydes and ketones respectively. Option D is the functional group for esters. Option E is known as a phenyl group, a benzene ring.