Final answer:
The auto-injector prescribed for a client with a history of allergies contains epinephrine, which is used to treat anaphylactic shock. Therefore, the correct option is d.
Step-by-step explanation:
The nurse understands that an auto-injector prescribed for a client with a history of allergies contains the drug epinephrine. This medication is vital for treating anaphylactic shock, a severe allergic reaction that can result in a rapid drop in blood pressure, breathing difficulties, and potentially fatal consequences if not treated promptly. Patients with known severe allergies often carry an epinephrine auto-injector, such as an EpiPen®, with them at all times to administer the life-saving drug immediately upon experiencing a reaction.