A 62-year-old, otherwise healthy, non-smoking woman presents to the clinic with a cough productive of green sputum for seven days. There is low-grade fever and scattered rhonchi on exam, with an oxygen saturation of 97% on room air. Which of the following is the most likely diagnosis?
A Acute bronchitis
B Acute exacerbation of COPD
C Pneumonia
D Upper respiratory infection
A. Acute Bronchitis