Prokaryotic cells typically measure 0.1–5 μm

Steps:

• Prokaryotes like bacteria range from 0.1 μm (100 nm) to about 5–10 μm in length or diameter.
• Most common sizes fall between 0.2 μm and 2 μm, with many under 1 μm.
• Convert units: 1 μm = 1,000 nm, so option B spans 0.1–1 μm.
• Compare ranges: B captures the majority of typical prokaryotic sizes.

Why B is correct:

• Prokaryotic cells are defined as unicellular organisms without nuclei, typically 0.1–1 μm for most bacteria like E. coli (about 0.5–2 μm but averaging under 1 μm in width).

Why the others are wrong:

• A: Too small; 1–100 nm covers viruses and macromolecules, not cells.
• C: Too large; 1–100 μm includes eukaryotic cells like animal cells (10–100 μm).
• D: Much too large; 100 μm–1 mm is visible to the naked eye, like some protists or multicellular structures.

Final answer: B