Identifying prokaryotic vs. eukaryotic cells

Steps:

• Examine the diagram for presence of a nucleus: absence indicates prokaryote.
• Check for membrane-bound organelles: lack suggests bacterium over eukaryotic cells.
• Note size and shape: small, rod or coccus form typical of bacteria.
• Rule out non-cellular entities: visible cell wall and cytoplasm point to bacterial cell.

Why B is correct:

• Bacteria are prokaryotes lacking a true nucleus and membrane-bound organelles, matching the diagram's simple structure per cell theory definitions.

Why the others are wrong:

• A: Animal cells are eukaryotic with a defined nucleus and no cell wall.
• C: Plant cells have chloroplasts, a large vacuole, and cellulose cell wall.
• D: Viruses are acellular, consisting only of nucleic acid in a protein coat, not a complete cell.

Final answer: B