Injection of antibodies provides artificial passive immunity

Steps:

• Classify immunity as active (body produces antibodies) or passive (receives ready-made antibodies).
• Distinguish natural (from natural processes) versus artificial (from medical intervention).
• Injection delivers pre-formed antibodies directly, making it passive.
• Since it's a deliberate medical procedure, it qualifies as artificial.

Why C is correct:

• Artificial passive immunity is defined as the transfer of antibodies from an external source, such as serum injections, providing immediate but temporary protection without stimulating the recipient's immune response.

Why the others are wrong:

• A: Artificial active involves vaccines that trigger the body's own antibody production, not direct antibody injection.
• B: Natural passive occurs through maternal transfer, like via placenta or breast milk, without medical intervention.
• D: Natural active results from recovering from an infection, where the body naturally produces antibodies.

Final answer: C