You are answering a USMLE-style medical question. Question: A 52-year-old man comes to the physician because of generalized pruritus and raised, erythematous plaques on the skin over his hands, chest, and legs for 6 hours. He reports having clear liquid discharge from his nose and sneezing. He says that his symptoms began suddenly the previous night, 30 minutes after he had dinner at a seafood restaurant. He has had similar symptoms occasionally in the past as well. Four months ago, he had an episode of narrow-angle glaucoma. He takes no medications. His vital signs are within normal limits. Nasal exam shows clear, serous secretions, with edematous and erythematous mucosa and turbinates. Paranasal sinuses are not tender to palpation. Which of the following is the most appropriate pharmacotherapy? Options: A) Diphenhydramine B) Fexofenadine C) Vitamin K D) Calamine lotion Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.