A nurse is caring for a client who has urticaria following administration of an antibiotic. Which of the following medications should the nurse prepare to administer?

A. Naloxone: Naloxone is an opioid antagonist used to reverse the effects of opioid overdose, such as respiratory depression. It is not effective in treating allergic reactions like urticaria caused by antibiotics. B. Diphenhydramine: Diphenhydramine is an antihistamine used to treat allergic reactions, including urticaria. It blocks histamine release, reducing itching, redness, and swelling associated with allergic responses. C. Hydralazine: Hydralazine is an antihypertensive medication used to treat severe high blood pressure. It has no role in managing allergic reactions and would not address the urticaria symptoms. D. Protamine: Protamine is used to reverse the effects of heparin in cases of overdose or bleeding. It does not counteract allergic responses and is not indicated for urticaria.