An alcoholic who presented with heaburn is diagnosed of having esophagitis. The MOST common cause of esophagitis is:

Esophagitis is defined as the presence of signs of inflammation of the esophageal mucosal surfaces, both macroscopically and microscopically. Gastroesophageal reflux disease (GERD) is the most common cause of esophagitis, followed closely by medication-induced and infection-induced inflammation. Ref: Chan W.W., Burakoff R. (2012). Chapter 154. Gastroesophageal Reflux Disease and Esophagitis. In G.V. Lawry, S.C. McKean, J. Matloff, J.J. Ross, D.D. Dressler, D.J. Brotman, J.S. Ginsberg (Eds), Principles and Practice of Hospital Medicine.