One sample is selected to represent scores in treatment 1 and a second sample is used to represent scores in treatment 2. Which set of sample statistics would present the clearest picture of a real difference between the two treatments?
a. Mean 1 = 32, Mean 2 = 38, both SD's = 15
b. Mean 1 = 20, Mean 2 = 30, both SD's = 15
c. Mean 1 = 30, Mean 2 = 40, both SD's = 5
d. Mean 1 = 20, Mean 2 = 25, both SD's = 5