A nutritionist investigates the impact of type of breakfast on mid-morning concentration. He puts together a sample of 50 adults. He feeds them a breakfast and 4 hours later measures their concentration on an interval level concentration test. On one day he feeds them bacon and eggs, on a second day he feeds them oatmeal, and on a third day he has them skip breakfast.

Select the appropriate statistical test from

(a) Single-sample z test;

(b) Single-sample t test;

(c) Independent-samples t test;

(d) Paired-samples t test;

(e) Between-subjects, one-way ANOVA; or

(f) none of the above.