The level of triglycerides in the blood rises when triglycerides are inadequately metabolized. Research shows that patients with blood triglyceride levels above 1 milligram per milliliter are twice as prone to heart attacks as others. Thus, it is likely that consuming large amounts of fat, processed sugar, or alcohol, each known to increase triglyceride levels in the blood, is a factor causing heart disease. Which one of the following, if true, most weakens the argument? ["Heart disease interferes with the body's ability to metabolize triglycerides.", 'People with a high-fat diet who engage in regular, vigorous physical activity are much less likely to develop heart disease than are sedentary people with a low-fat diet.', 'People who maintain strict regimens for their health tend to adopt low-fat diets and to avoid alcohol and processed sugar.', 'Triglyceride levels above 2 milligrams per milliliter increase the risk of some serious illnesses not related to heart disease.']