Which condition occurs when the immune system is unable to fight disease and protect the body?

• A. Allergies
• B. Immunodeficiency Diseases
• C. Autoimmune Disorders
• D. Infectious diseases

Answer: (B)

The situation being described is when the immune system can’t mount a strong defense against infections and illnesses. That diminished ability to fight disease is what immunodeficiency diseases are all about. They can be present from birth or develop later, and they weaken the body's defenses, making infections more common or severe.

Allergies involve the immune system overreacting to harmless substances, not a failure to protect. Autoimmune disorders are when the immune system targets the body’s own tissues. Infectious diseases are caused by pathogens like bacteria or viruses; they occur regardless of immune status, though a weakened immune system can make them harder to overcome.