Which of the following correctly ranks the size of viruses relative to bacteria, prions, and viroids, from largest to smallest?

• A. Prions > Viroids > Viruses > Bacteria
• B. Viruses > Bacteria > Prions > Viroids
• C. Bacteria > Viruses > Viroids > Prions
• D. Viroids > Prions > Bacteria > Viruses

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the size ranges of each entity. Bacteria are single-celled organisms typically ranging from about 0.5 to 5 micrometers (µm) in size.
2. Step 2: Viruses are smaller than bacteria, generally ranging from about 20 to 300 nanometers (nm), which is 0.02 to 0.3 micrometers.
3. Step 3: Viroids are even smaller than viruses; they are small infectious RNA molecules, usually about 250 to 400 nucleotides long, roughly a few nanometers in size.
4. Step 4: Prions are misfolded proteins and are the smallest infectious agents, smaller than viroids, typically on the order of a few nanometers or less.
5. Step 5: Based on these size ranges, rank them from largest to smallest as: Bacteria > Viruses > Viroids > Prions.