Reynaldo is reviewing a study on the effectiveness of a new drug-ree remedy for depression In the study a group of participants was given a natural supplement for a period of sik weoks. They rated their mood both before and after treatment. Two-thirds of tne group reported a marked improvement after the trial. What change in this study would do the most to increase Reynaldo's confidence that sound s were followed? A. Including a control group that did not receive the supplement
B. Including information about the manufact
C. Including testimony of participants in the study's documentation and cost of the If-reported mood ratings