Which molecule is completely absent from a prion?

1. A prion is an infectious particle made of protein. 2. It replicates without DNA and without RNA, so it carries no nucleic acid at all. 3. That is why it was long thought impossible for such an agent to exist. 4. Protein is the one thing a prion is built from, so the protein options are the opposite of the answer. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 21 "Viruses", section 21.4 Other Acellular Entities: Prions and Viroids_