Secondary Immune Response Plateau

Steps:

• Person G shows primary response; infection on day 20 triggers new antibody rise starting around day 25-30.
• Person H shows secondary response from prior exposure; levels already high by day 20.
• Infection on day 20 boosts H's response minimally due to existing memory cells.
• Antibody levels in H remain elevated, stabilizing at the day 32 peak without further increase.

Why B is correct:

• Secondary responses maintain high antibody titers post-boost, per immunological memory principles, keeping H at day 32 levels.

Why the others are wrong:

• A: G produces antibodies via primary response activation.
• C: Secondary peaks match or exceed primaries, not lower.
• D: No antibodies produced on day 0 in G; response lags.

Final answer: B