Treatments may be a combination of factors rather than a single factor. For example, suppose we want to investigate the role of diet and drugs in weight loss. Suppose we have three diet plans (a saturated-fat diet, the Mediterranean diet, or the U.S. National Cholesterol Education Plan, or NCEP-1 Diet) along with a new experimental weight-loss drug versus a placebo. So, diet has three treatment levels and drug has two treatment levels. Determine the six treatments that consider all possible combinations of these two factors.