What is an allergy?

An allergy is characterized by an exaggerated immune response to substances that are typically harmless to the majority of people. In this context, the correct answer accurately defines an allergy as a reaction due to extreme sensitivity to certain foods, chemicals, or other normally harmless substances. When an individual with an allergy encounters an allergen—such as pollen, pet dander, certain foods, or medications—the immune system mistakenly identifies these substances as threats, leading to various symptoms that can range from mild to severe.

Understanding this definition is crucial for professionals in the lash specialty field because they need to be aware of potential allergens in products they use, such as adhesives or cleaning solutions. It helps ensure both their safety and that of their clients.

The other options describe different conditions or responses that do not encompass the specific nature of allergies. For instance, an infection caused by a virus pertains to a pathogenic attack on the body rather than an immune system overreaction. Similarly, a response to chemical agents might involve irritation or toxicity rather than the hypersensitivity that characterizes an allergic reaction. The term "reaction to extreme sensitivity to certain harmful substances" may imply a broad range of responses, but it doesn’t capture the essence of allergies as they are typically harmless substances. Thus, the selected