Final answer:
Hydroxyzine is prescribed before surgery primarily for its anti-anxiety effects, not for emesis control, narcotic reduction, thrombus prevention, or drying secretions.
Step-by-step explanation:
The nurse should explain to the client that the medication hydroxyzine is prescribed for diminishing anxiety prior to surgery. Hydroxyzine is an antihistamine with anti-anxiety properties. While antihistamines like hydroxyzine primarily block the action of histamine at H1 receptors and prevent symptoms like itching and swelling (part C), some antihistamines, also have sedative properties and can reduce anxiety (part B). Although hydroxyzine has some sedating properties, and in higher doses can function as a narcotic, it is not specifically prescribed for reducing the amount of narcotics needed for pain relief (part C) or for preventing thrombus formation (part D). Furthermore, while drying secretions (part E) may be one of the effects, it is not the primary reason hydroxyzine is administered before surgery.