Researchers wanted to determine if having a refrigeratorrefrigerator in the bedroom is associated with obesity. The researchers administered a questionnaire to 364364 ​twelve-year-old adolescents. After analyzing the​ results, the researchers determined that the body mass index of the adolescents who had a refrigeratorrefrigerator in their bedroom was significantly higher than that of the adolescents who did not have a refrigeratorrefrigerator in their bedroom. Complete parts​ (a) through​ (e) below. Question content area bottom Part 1 ​(a) Why is this an observational​ study? What type of observational study is​ this? Why is this an observational​ study?