You are answering a USMLE-style medical question. Question: In a small town with a population of 10,000 people, the prevalence of alcohol use is estimated to be 30%. A study is done with a null hypothesis that there is no association between alcohol use and gastro-oesophageal reflux disease (GERD). The data obtained shows, of the 200 alcoholics who were followed-up, 30 developed GERD; and out of the 400 non-alcoholics, 30 developed GERD. What fraction of GERD can be prevented in the general population if alcohol is no longer consumed in this town? Options: A) 45/195 B) 30/400 C) (30/200) / (30/400) D) 30/200 Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.