A 22-year-old has nasal congestion, runny nose and post nasal drip. The symptoms recur each year in the spring. There is no facial pain/pressure, mucopurulent nasal discharge, or epistaxis. On exam, there is bilateral clear rhinorrhea with boggy, pale mucosa of the nasal cavities. The patient has a history of mild asthma. Skin prick testing shows allergies to multiple tree species. Which of the following is best to treat the runny nose? A. Oral prednisone B. Diphenhydramine C. Nasal glucocorticoid D. Azithromycin E. Nasal cromolyn