The south beach diet was given to a volunteer group of 25 people who were atleast 25 pounds overweight. eighteen people from the group lost atleast 20 pounds. what should we conclude about the effectiveness? a. nothing, since the group knew they were using the diet. b. the diet is effective in 72% of people. c. nothing, since the 25 people were not an srs. d. nothing, since there was no control group. e people overweight by atleast 50 pounds will lose more than 20 pounds on the diet