Answer:
A. Allergies make a person react to substances in the environment that are harmless to most people but are harmless to the person reacting. Allergic reactions begin in your immune system. When a harmless substance such as dust, mold, or pollen is encountered by a person who is allergic to that substance, the immune system may overreact by producing antibodies that "attack" the allergen.
B. This medication works by blocking a certain natural substance (histamine) that your body makes during an allergic reaction.
C. It can cause a drying effect mouth and eyes, sedation, and sleepiness. However, it can impair innate immune responses to bacteria, and that these drugs should be used with caution in patients with severe bacterial infections.
D. ---
Explanation:
The video was not linked so I can't really answer D for you. Also, I'm sure you're aware of your own allergies. Good luck!