Cobblestoning of the posterior pharynx. A 52-year-old woman comes to the physician because of an 8-month history of an intermittent nonproductive cough. She takes no medications. She has smoked one pack of cigarettes daily for 25 years. She has had three episodes of sinusitis over the past 18 months. Examination shows pale nasal mucosa and cobblestoning of the posterior pharynx. The lungs are clear to auscultation. There is no clubbing or cyanosis. Which of the following is the most likely cause of this patient's cough? A) Allergic rhinitis B) Bronchiectasis C) Chronic bronchitis D) Hypersensitivity pneumonitis E) Rhinitis medicamentosa