The correct option is B Histamine
Histamine is a chemical stored within our body. It is produced by cells known as mast cells. Histamine is a protein molecule with the chemical formula C5H9N3. It serves as an important part of our body's immune response. When we come into contact with an allergen, such as pollen or animal dander, histamine is released by the body to the site of contact. The intention of this response is to help the body deal with the irritation caused by the allergen. Strangely enough, the histamine released actually causes allergic symptoms. So, the correct answer is option B.