Final answer:
In the case of a mild allergic reaction, Benadryl, an antihistamine, would be the appropriate medication to administer.
Step-by-step explanation:
After a mild allergic reaction to contrast, the doctor would likely choose an antihistamine to treat the symptoms. Among the options provided, a. Benadryl (generic name: diphenhydramine) is an appropriate antihistamine. Antihistamines work by either preventing mast cells from releasing histamines (b. Antihistamines prevent mast cells from releasing histamines) or blocking the action of histamines that have already been released (c. Antihistamines prevent histamines that have been released by mast cells), hence, calming the allergic symptoms. Benadryl is commonly used for the treatment of mild allergy symptoms and would be selected over adrenalin (epinephrine), Xylocaine (lidocaine), or atropine, which are used in other medical contexts.