Question

A noninfectious unnatural and unusual reaction to a substance or condition is?
A) Immunity
B) Allergy
C) Infection
D) Toxin            

Answer 1

Hint: Hypersensitivity is an exaggerated immune response that results in tissue damage and is manifested in the individual on second or subsequent contact with the antigen. These are treated by antihistamines, epinephrine, and steroids like cortisone.


Complete step-by-step answer:

Type I hypersensitivity also called an allergic reaction is induced by antigens referred to as allergens. The term allergen specify to nonparasitic antigens capable of stimulating an unusual reaction to a substance i.e., type I hypersensitive responses. Type I hypersensitive reactions are Ig-E mediated humoral antibody responses. These Ig-E mediated reactions are stimulated by the binding of Ig-E to high-affinity Ig-E specific Fc receptors expressed on mast cells and basophils. When cross-linked by antigens, the Ig-E antibodies trigger the mast cells and basophils to release primary mediators, vasoactive amines, stored in the granules( degranulation). Some examples of allergies are hay fever, food allergies, allergic eczema, and asthma.
Immunity: The ability of an organism to resist infections by pathogens or a state of protection against foreign organisms or substances is called immunity.
Toxin: It is a poison of plant or animal origin, especially one produced by or derived from microorganisms and acting as an antigen in the body.
Infection: The attack and growth of germs in the body are called infections. The germs may be bacteria, viruses, yeast, fungi, or other microbes. Infections can be anywhere in the body and may spread throughout the body.


Therefore the correct answer is Option B.

Note: Type I hypersensitivity can be anaphylaxis or atopy, anaphylaxis is a rapid, life-threatening, severe whole-body allergic reaction. Exposure to a previously encountered antigen also causes allergy. Atopy ( atopic allergy) is a hereditary tendency to develop an allergic reaction to a substance such as pollen, food, insect, or venom.