Question

which of the following is defined as any substance capable of inducing an immune response?

antigen.
allergen.
antibody.
toxin.

Explanation:

Define the core immunological terms

Using the Immune Response knowledge point

• Antigen: Any substance (typically foreign) that binds specifically to components of the immune system (like antibodies or T-cell receptors) and is capable of inducing an immune response.
• Allergen: A specific type of antigen that produces an abnormally vigorous immune response (allergic reaction) in which the immune system fights off a perceived threat that would otherwise be harmless.
• Antibody: A protective protein produced by B lymphocytes in response to the presence of a specific antigen.
• Toxin: A poisonous substance produced within living cells or organisms.

Identify the matching definition

The question asks for the definition of "any substance capable of inducing an immune response." This broad definition matches the term Antigen.

Answer:

• Antigen. (Correct answer)
• Allergen.
• Antibody.
• Toxin.