This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anitibody, Subject name: Microbiology
Which antibody is most commonly produced in secondary immune response? 
Select and explain. 
A. IgG, B. IgA, C. IgD, D. IgM
A: IgG
Answer: A: IgG 
Explanation: Ans. (a) IgGRef: Jawetz 24/e, chapter 8