A 24-year-old has been taking over-the-counter diphenhydramine for allergic rhinitis, and recently the increase the dose of the medication they ask a friend who is a graduate nursing student to explain why they feel sleepy, or lately. What is the most likely answer regarding diphenhydramine? A. Diphenhydramine blocks H1 receptors in the brain B. Diphenhydramine blocks the H2 receptors in the gut C. Diphenhydramine acts peripherally, since it does not cross the blood brain barrier D. Diphenhydramine inhibits the release of dopamine and serotonin