Final answer:
An allergic reaction is the immune system's overreaction to a harmless substance, known as an allergen, and is classified as a type I hypersensitivity reaction.
Step-by-step explanation:
This type of contamination is an overreaction of the immune system to an unwanted substance, and the correct answer is (d) Allergic reaction. An allergic reaction is an immune response where the body's immune system mistakenly targets a harmless substance known as an allergen. These allergens, such as pollen, dust mites, specific foods, or insect stings, trigger symptoms that can be mild to severe and do not pose a threat to most individuals. Allergic reactions are classified as type I hypersensitivity reactions. An allergy is not like other types of contamination, such as physical, biological, or chemical, because it specifically involves the immune system's maladaptive response.