A researcher in Idaho was interested in testing three potential medicines for COVID ( medicine A, B and C). He took a random sample of 5 Covid patients from each hospital in the United States and randomly assigned each patient to take one of the three Covid medicines. He then monitored their symptoms and how long it took them to recover. Use this information for all parts. Part 1: is this an example of an experiment or observational study? A. An observational study because all the subjects were Covid patients B. An observational because the subjects were randomly chosen. C. An experiment because a comparison is being made D. An experiment because the subjects were randomly assigned to take one of the medicines. Part 2: what type of sampling method was used when randomly gathering coronavirus from each of the major countries experiencing problems? A. Simple random sample( SRS) B. Cluster C. Systematic D. Stratified E. Convenience Part 3: what is the population of this study? A. All people in the world who have Covid. B. All the coronaviruses in the world. C. All the Covid patients in the United States. E. The randomly chosen people from the hospitals in the United States