Answer:
Histamine
Step-by-step explanation:
Histamine is a chemical that is released by cells in the body in response to an allergic reaction. It is produced by cells called mast cells and basophils, and it is stored in granules within these cells. When an allergen enters the body, it triggers the release of histamine, which then causes inflammation and increased mucus production. This results in the classic symptoms of an allergic reaction, such as itching, swelling, and increased mucus production.