A recent study of college students shows that, contrary to predicted results, special nutritional planning does not positively affect students’ grades. Sixty students, half of whom were given a nutritionally balanced diet, had grades no higher than did those students who were not placed on the diet plan.

Which of the following, if true, is most useful in determining the accuracy of the study described above?


a) Performance of business executives was shown to improve drastically after major alterations were made in their diets.

b) Honors students, after altering their diets, maintained that they did not change their study habits.

c) Students who participated in various fitness regimens found that their grades improved appreciably after they altered their exercise habits.

d) High school students who previously had low grades found that after they altered their diets, their grades improved dramatically.

e) All of the college students who volunteered for the study were either in their first or second year of college.

can some one help me ans this. My ans was b, however, the OA is d

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