D A researcher was interested in studying the effect of good sleep on beauty. He divided the population of adults into 4 age groups, he then randomly chose 20 adults from each group to participate in the study. Participants were photographed after a normal night's sleep (eight hours) and after forcing them to stay awake (31 hours of wakefulness after a night of reduced sleep). Experts then rated their photographs using a standardized beauty scale. Use this information to answer both parts below. D Question 6 1 pts Part 1: Is this an observational study or an experiment? Experiment, because the researcher had control of who was included in the study. O Observational study, because the researcher does not try to interfere with the subjects or influence the results in any way. O Experiment, because the researcher influenced the outcomes by making the subjects sleep or not sleep. g Hide Observational study, because the researcher's data is categorical