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
Borrelia undergoes antigenic variation due to: 
Select and explain. 
A. Plasmids, B. Transposons, C. Intrinsic mutation, D. All of the above
A: Plasmids
Answer: A: Plasmids 
Explanation: Ans. is. 'a' i. e., Plasmids