Statistics students take a SRS of 45 from their school population. They separate the students into two groups, those who admit to smoking marijuana and those who say they don't. The student researchers then attain the GPA of each student and compare the mean GPA of each group. a. Is this an experiment or an observational study? Explain. b. Are there any possible sources of bias? Explain. c. If the marijuana group has a significantly lower mean GPA than the other group from this experiment/study can we attribute that to the marijuana? Explain