Researchers recruited more than 750 adults and asked them to wear a new design of shoe. Half of the subjects were randomly assigned to a name-brand shoe, while the other half were assigned to a shoe with no name on the label. On average, the shoes with the brand name were judged to be more comfortable. Based on this study, is it reasonable to conclude that including the brand name on the label causes an increase in comfort?

a. No, association does not imply causation.
b. No, there was no control group for comparison.
c. No, the adults were not randomly selected from the population of all adults.
d. Yes, the adults were randomly assigned to the treatments.
e. Yes, there was a large number of adults involved in the study.