I - _ Disease Incidence per 1,000 Persons per year Myocardial infarction _-:- The data from the above table is from a prospective studyr that examined the relationship between smoking and incidence of both myocardial infarction (heart attack) and breast cancer among women. Among smokers, approximately what proportion of breast cancer is due to smoking? Select one: a. 20% b. 40% c. 50% d. 60%