Doctors urge people to reduce their cholesterol levels through dietary changes. But moderate dietary changes often do not work to lower cholesterol levels. One may need, ttherefore, to make more dramatic changes, such as switching to a vegetarian diet. The statement that moderate dietary changes often do not work to lower cholesterol levels plays which one of the following roles in the argument? ['It is offered as an explanation of the success of vegetarian diets in reducing cholesterol levels.', "It is a conclusion for which the claim that dramatic changes in one's diet are sometimes required to reduce cholesterol levels is offered as support.", 'It is a premise offered in support of the claim that reducing cholesterol levels may require greater than moderate dietary changes.', 'It is a premise offered in support of the claim that vegetarian diets are more healthful than any diets containing meat.']