Which of the following terms refers to noncellular infectious protein particles?

• A. Viroids
• B. Viruses
• C. Prions
• D. Bacteriophages

Answer: (C)

Verified step by step guidance

1. Understand the definitions of each term: Viroids are small infectious RNA molecules that affect plants; Viruses are infectious agents composed of nucleic acid (DNA or RNA) enclosed in a protein coat; Bacteriophages are viruses that specifically infect bacteria; Prions are infectious protein particles without nucleic acids.
2. Identify the key characteristic in the question: 'noncellular infectious protein particles' means the infectious agent is made only of protein and lacks nucleic acids.
3. Compare each option against this characteristic: Viroids contain RNA, Viruses contain nucleic acids and protein, Bacteriophages are viruses with nucleic acids, and Prions are solely protein-based infectious agents.
4. Conclude that the term matching 'noncellular infectious protein particles' is Prions, as they are unique infectious agents composed only of misfolded proteins.
5. Remember that prions cause diseases by inducing abnormal folding of normal proteins, which distinguishes them from other infectious agents that contain nucleic acids.