Eating garlic reduces the levels of cholesterol and triglycerides in the blood and so helps reduce the risk of cardiovascular disease. Evidence that eating garlic reduces these levels is that a group of patients taking a garlic tablet each day for four months showed a 12 percent reduction in cholesterol and a 17 percent reduction in triglycerides; over the same period, a group of similar patients taking a medically inert tablet showed only a 2 percent reduction in triglycerides and a 3 percent reduction in cholesterol. It would be most important to determine which one of the following in evaluating the argument? ['whether the garlic tablets are readily available to the public', 'what the diets of the two groups were during the period', 'what effect taking the garlic tablets each day for a period of less than four months had on the levels of cholesterol and triglycerides', 'whether large amounts of garlic are well tolerated by all patients']