Alcohol consumption has been clearly linked to high blood pressure, which increases the likelihood of developing heart disease. Yet in a study of the effects of alcohol consumption, the incidence of heart disease was lower among participants who drank moderate quantities of alcohol every day than it was among participants identified as nondrinkers. Which one of the following, if true, most helps to resolve the apparent discrepancy in the information above? ['Some of the participants who drank moderate quantities of alcohol every day had high blood pressure.', 'Many of the participants identified as nondrinkers were people who had been heavy drinkers but had stopped drinking alcohol prior to participating in the study.', "The two groups of participants were similar to each other with respect to the participants' age, sex, geographical origin, and economic background.", 'Because many people who do not drink alcohol are conscious of their health habits, they are likely to engage in regular exercise and to eat nutritionally well-balanced meals.']