Answer: Option (b) is the correct answer.
Step-by-step explanation:
A functional group that contains "-COOH" is known as a carboxylic acid. Therefore, a compound which contains carboxylic acid will have suffix "-ic" as the identity of the functional group present in it.
Formaldehyde: It has an aldehyde (CHO) group as the functional group.
Formic acid: It has a carboxylic (COOH) group as the functional group.
Acetone: It has ketone (C=O) as the functional group.
Carbon Hydroxide: A compound that contains carbon and hydroxide (OH) group as the functional group is known as alcohol.
Thus, we can conclude that HCOOH is formic acid.