4. In clinical trials of the cholesterol drug Lipitor, A group of 368 subjects were randomly assigned to two groups: Group 1 containing 188 subjects who were given 20-mg doses of the drug for two weeks, and symptoms of nausea and dizziness were measured. While a group of 180 subjects were given a placebo pill for two weeks, and symptoms of nausea and dizziness were measured. a. Determine if this is an experiment or an observational study. Explain your reasoning. b. List the explanatory and response variables in this study. c. Why do researchers use random assignment in this study? Explain the practical purpose of using random assignment. d.. Provide an example of at least two confounding variables. e. Can we use the results of this study to establish a cause-and-effect claim between Lipitor use and an increase in symptoms of nausea and dizziness? Explain your reasoning