Consider the following statements with repect to allergy.
A. Allergy is due to the release of chemicals like heparin and adrenaline from the mast cells.
B. The exaggerated response of the immune system to certain antigens present in the environment is called allergy.
C. The use of chemicals like anti-histamine, adrenaline and steroids aggravate the symptions of allergy.
D. Common examples of allergens are mites in dust, pollens, animals dander, etc.