Evaluating immunity statements for accuracy

Steps:

• Assess statement 1: Memory cells form during active immunity via immune response; passive immunity transfers pre-formed antibodies without producing memory cells.
• Assess statement 2: Antibodies target specific antigens on pathogen surfaces or within infected cells, triggering B-cell production.
• Assess statement 3: Antibodies bind antigens via complementary shapes, not identical ones, following the lock-and-key model.
• Determine correct statements: Only statement 2 holds true, matching option D.

Why D is correct:

• Statement 2 aligns with immunological definition: Antibodies are produced by plasma cells in response to antigens on pathogens or infected cells.

Why the others are wrong:

• A includes incorrect statement 1, as memory cells require active immunity exposure.
• B includes incorrect statement 1 and 3, ignoring complementary antibody-antigen binding.
• C includes incorrect statement 3, which misstates antibody shape as identical rather than complementary.

Final answer: D