Molecules in cytoplasmic structure

Steps:

• Identify the structure as a ribosome based on electron micrograph features like small dense granules in cytoplasm.
• Recall ribosomes consist of rRNA and proteins, no DNA or lipids primarily.
• Assume labels: 1=DNA, 2=protein, 3=lipid (common in such questions).
• Match: only protein (2) is present.

Why D is correct:

• Ribosomes contain ribosomal proteins bound to rRNA, per cell biology definition of ribosomal composition.

Why the others are wrong:

• A includes 1 (DNA) and 3 (lipid), absent in ribosomes.
• B includes only 1 (DNA), not found in cytoplasmic ribosomes.
• C includes 2 (protein) and 3 (lipid), but lipids are not structural components.

Final answer: D