Can changing the diet reduce high blood pressure? vegetarian diets and low-salt diets are both promising. men with high blood pressure are assigned at random to four diets: (1) normal diet with unrestricted salt; (2) vegetarian with unrestricted salt; (3) normal with restricted salt; and (4) vegetarian with restricted salt. (a) what are the factors (explanatory variables) in this experiment? there are no factors. there is one factor: diet (normal, vegetarian). there is one factor: salt (restricted, unrestricted). there are two factors: diet (normal, vegetarian) and salt (restricted, unrestricted). there are four factors: the four diets being compared.