Final answer:
An allergy is when the immune system overreacts to a harmless substance, producing IgE antibodies that cause inflammation and symptoms that can range from mild to life-threatening. The correct statement is 'Allergies can cause harm to the host without conferring a survival advantage.'
Step-by-step explanation:
An allergy is essentially an inappropriate immune reaction to a substance that is usually harmless. When a person is initially exposed to an allergen, the immune system mistakenly identifies it as a threat and produces IgE antibodies. These antibodies then sensitize mast cells. During subsequent exposures, the allergen binds to the IgE antibodies on the mast cells, causing the release of histamine and other chemicals that lead to inflammation and other allergic reactions. These reactions can include mild symptoms like sneezing and watery eyes or severe responses such as anaphylactic shock, which can be fatal if not treated promptly with epinephrine.
The correct answer to the question is 'd) Allergies can cause harm to the host without conferring a survival advantage.', as allergies do not protect the body from pathogens but can indeed cause harm. Allergic reactions are to harmless proteins in the environment that the body unnecessarily targets, leading to various unpleasant symptoms and potentially dangerous health consequences.