Final answer:
Prions are infectious agents composed entirely of protein and contain no nucleic acids, causing diseases by altering the folding of other normal proteins in the brain.
Step-by-step explanation:
Prions are unique infectious agents that challenge our traditional understanding of what it takes to be an infectious particle. Unlike viruses, which consist of nucleic acids surrounded by a protein coat, or capsid, prions contain no DNA or RNA. The correct answer to your question is B) are made of protein only. Prions are purely protein-based and have a structure that allows them to replicate by causing other normal proteins to misfold in the same way, leading to a cascade of misfolding events and subsequent cellular damage.
This disruptive process can result in progressive brain disorders such as mad cow disease and Creutzfeldt-Jakob disease. Thus, prions are essentially misfolded versions of normal proteins that can induce other proteins to adopt their misfolded shape, contributing to disease.