Natural Active Immunity via Repeated Infections

Steps:

• Recognize repeated malaria infections as natural exposure to the pathogen.
• Note this exposure stimulates the body's own antibody production.
• Classify as active immunity since the immune system actively responds.
• Confirm it's natural, not involving medical intervention like vaccines.

Why C is correct:

• Natural active immunity develops when the body encounters and fights a real pathogen, like malaria, producing long-lasting antibodies for future protection.

Why the others are wrong:

• A: Artificial active immunity comes from vaccines, not direct infection.
• B: Artificial passive immunity involves injected pre-formed antibodies, providing short-term protection without body activation.
• D: Natural passive immunity transfers antibodies from mother to baby, unrelated to personal infections.

Final answer: C