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. True statement is: 
Select and explain. 
A. Defect in protein folding, B. Cleave proteins, C. Scarpie is a human disease, D. Are non infectious
A: Defect in protein folding
Answer: A: Defect in protein folding 
Explanation: Defect in protein folding