Nucleic acids are primarily in the nucleus

Steps:

• Identify nucleic acids as DNA and RNA, key genetic molecules.
• Locate DNA in the cell nucleus (structure 1), which stores genetic information.
• Note RNA is synthesized in the nucleus but functions elsewhere; however, the question focuses on containment in specific structures.
• Eliminate options including 2, 3, or 4, as they likely represent non-nucleic acid structures like cytoplasm, mitochondria without specifying, or vacuoles.

Why C is correct:

• Structure 1 (nucleus) contains both DNA and RNA, per cell biology definitions of nuclear composition.

Why the others are wrong:

• A includes 2 and 3, which do not contain nucleic acids.
• B adds 4, typically a organelle without nucleic acids like lysosomes.
• D selects 2 and 4, neither housing nucleic acids.

Not enough information on exact structures 2–4, but based on standard biology, C fits.

Final answer: C