Dietitian: It is true that nutrients are most effective when provided by natural foods rather than artificial supplements. While it is also true that fat in one' s diet is generally unhealthy, eating raw carrots (which are rich in beta carotene) by themselves is nonetheless not an effective means of obtaining vitamin A, since the body cannot transform beta carotene into vitamin A unless it is consumed with at least some fat. The statement that fat in one's diet is generally unhealthy plays which one of the following roles in the dietitian's argument? ['It is mentioned as a generally accepted hypothesis that the dietitian attempts to undermine completely.', 'It is mentioned as a reason for adopting a dietary practice that the dietitian provides a reason for not carrying to the extreme.', 'It is cited as a bad reason for adopting a dietary habit that the dietitian recommends.', 'It is attacked as inadequate evidence for the claim that nutrients are most effective when provided by natural foods rather than artificial supplements.']