A weight loss program provides three follow-up methods to choose from for individuals who went through the program and reached their desired weight monthly in person meeting monthly on line meeting and monthly newsletter by mail. In order to assess the effectiveness of the three follow-up methods, the program selects a random sample of 291 individuals who went through the program and reached their desired weight and classifies them according to the follow-up method that they sign-up for. A year later the study finds that 30% of those who chose to sign up for the in person follow-up method regained more than 5 pounds, son of those who chose to sign up for the online method regained more than 5 pounds and 70% of those who chose to sign up for the newsletter method regained more than 5 pounds Which of the following is the correct design of this study?
a. An observational study
b. A randomized response study
c. A randomized experiment
d. A randomized observational study
e. A blind observational study