Which of the following research situations is most likely to use a between-subjects design?
a. Evaluation of the effectiveness of an exercise program by measuring how much
b. weight is lost during 6 months of strength training
c. Evaluation of the effectiveness of a blood pressure medication by comparing blood pressure before the medication, 3 months after, and again 6 months after the medication.
d. Evaluation of the difference in verbal skills between 2-year-old, 4-year-old, 6-year-old boys
e. Evaluation of the development of verbal sklls between age 2 and age 6 for a sample