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
Antibody diversity is due to -a) Gene rearrangementb) Gene translocationc) Antigenic variationd) CD40 moleculese) Mutation 
Select and explain. 
A. ace, B. bde, C. cde, D. ade
A: ace
Answer: A: ace 
Explanation: None