Step 1: Structure of salicylaldehyde.
Salicylaldehyde consists of a benzene ring with two functional groups: an aldehyde group (-CHO) and a hydroxyl group (-OH). These two functional groups contain a total of two oxygen atoms.
Step 2: Analyzing the options.
(A) 3: Incorrect — There are only two oxygen atoms in salicylaldehyde.
(B) 1: Incorrect — There are two oxygen atoms.
(C) 2: Correct — The two oxygen atoms are in the aldehyde and hydroxyl groups.
(D) 4: Incorrect — There are only two oxygen atoms in the molecule.
Step 3: Conclusion.
The correct answer is (C) 2.