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
True about prions: 
Select and explain. 
A. Composed largely proteins without any nucleic acid, B. Phase in which virus cannot be demonstrated in host cell, C. Viruses which are genetically deficient, D. Viral components may be synthesized but maturation & assembling is defective.
A: Composed largely proteins without any nucleic acid
Answer: A: Composed largely proteins without any nucleic acid 
Explanation: None