Blood Components' Roles in Fighting Pathogens

Steps:

• Identify blood components: red blood cells transport oxygen, white blood cells fight infection, platelets aid clotting.
• Recall white blood cell types: lymphocytes produce antibodies, phagocytes engulf pathogens.
• Match question to function: fighting pathogens involves direct destruction or neutralization.
• Select component that directly combats via ingestion: phagocytes.

Why B is correct:

• Phagocytes, such as neutrophils and macrophages, engulf and digest pathogens through phagocytosis, a key immune defense mechanism.

Why the others are wrong:

• A. Lymphocytes produce antibodies and coordinate immunity but do not directly engulf pathogens.
• C. Platelets promote blood clotting to prevent bleeding, not pathogen fighting.
• D. Red blood cells carry oxygen and have no role in immune defense.

Final answer: B