Extreme hypersensitivity reaction to a substance that can lead to shock and life-threatening respiratory collapse.

• A. Allergy
• B. Anaphylaxis
• C. Angina
• D. Asthma

Answer: (B)

Anaphylaxis is a severe, widespread allergic reaction that can rapidly cause shock and life-threatening trouble breathing. It happens when the immune system overreacts to a substance, releasing chemicals that trigger widespread swelling, very low blood pressure, and narrowing of the airways. Because these effects happen quickly and affect many parts of the body at once, it can lead to fainting or respiratory collapse if not treated right away.

This is different from a general allergy, which is any immune response to an allergen but isn’t necessarily life-threatening or systemic. Angina is chest pain caused by reduced blood flow to the heart, not an allergic reaction. Asthma involves chronic airway inflammation and wheezing, but it’s typically not characterized by the sudden, body-wide shock that defines anaphylaxis.