An education company representative speaking on a local news station has advocated that high school students download a particular app on their phone. The individual cited a study of 800 randomly selected high school junior and senior students that reported that students who downloaded the app on their phones, on average, scored 50 points higher on a standardized test than those who did not download the app. Which of the following statements is correct?

A.Because downloading the app seems to improve standardized test scores for high school students, the app should be effective for middle school students.

B.Downloading the app will cause a student to score higher on an AP Statistics exam.

C.The study was an experiment rather than an observational study.

D.There seems to be a relationship between the app and obtaining a higher score on the standardized test.

E.The sample size of the study was too low to determine a result.