A Major Cohort Research Is Being Done to Examine the Relationship

A major cohort research is being done to examine the relationship between smoking and esophageal squamous cell cancer in middle-aged Chinese males. During a 10-year follow-up, smokers had a 5 times higher incidence of esophageal cancer than nonsmokers (relative risk = 5.0, 95 percent confidence range = 2.9-7.1) . What proportion of squamous cell carcinoma of the esophagus among smokers may be related to smoking, according to the research findings?

A) 25%
B) 50%
C) 70%
D) 80%
E) 90%