The graph below depicts serum antibody levels in a child after vaccination. Which antibody types do the curves A and B represent, respectively?

• A

  $\operatorname{IgA}, \operatorname{IgM}$.
• B

  $\operatorname{IgM}, \operatorname{IgG}$.
• C

  $\operatorname{Ig} A, \operatorname{IgE}$.
• Correct answer
  D

  IgG, IgM.

Hence, the correct answer is option: 'D'.