Question

a person who has a weakened immune system may not be able to fight against infection because
○ pathogens may enter the body and cause illness.
○ phagocytes may enter the body and cause illness.
○ normal cells crowd out unhealthy cells.
○ antibodies production is increased.

Explanation:

1. Analyze each option:

• Option 1: Pathogens are disease - causing agents. A weakened immune system can't effectively defend against them, so they enter and cause illness. This makes sense.
• Option 2: Phagocytes are part of the immune system that helps fight infection, they don't cause illness.
• Option 3: A weakened immune system is about not being able to fight, not normal cells crowding out unhealthy cells (this is not related to immune system weakness in fighting infection).
• Option 4: A weakened immune system would likely have decreased antibody production, not increased.

Answer:

A. pathogens may enter the body and cause illness.