This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Prions consist of: 
Select and explain. 
A. DNA and RNA, B. DNA, RNA and proteins, C. RNA and proteins, D. Only proteins
D: Only proteins
Answer: D: Only proteins 
Explanation: Ans. (d) Only protein