In each of the following settings, identify the explanatory and response variables. Then determine if each is an experiment or an observational study. Explain your reasoning. a. In a study conducted by researchers at the University of Texas, people were asked about their social media use and satisfaction with their marriage. Of the heavy social media users, 32% had thought seriously about leaving their spouse. Only 16% of non-social media users had thought seriously about leaving their spouse. b. In a diet study using 100 overweight volunteers, 50 volunteers were randomly assigned to receive weight-loss counseling, monthly weigh-ins, and a three-month gym pass. The other 50 volunteers were given financial incentives (earning $20 for losing 4 pounds in a month or paying $20 otherwise) along with the counseling, weigh-ins, and gym pass. The group with the financial incentives lost 6.7 more pounds, on average. PROBLEM: In a study of more than 4700 children, researchers from Cincinnati Children's Hospital Medical Center found that those children whose mothers smoked during pregnancy were more than twice as likely to develop ADHD as children whose mothers had not smoked. Explain how confounding makes it unreasonable to conclude that a mother's smoking during pregnancy causes an increase in the risk of ADHD in her children based on this study