Help with parts a,b,c,d

Problem #2 A researcher is interested to determine the percentage of students in Washington state who feels comfortable about taking face-to-face courses in Fall 2022. Due to a large number of students in Washington, the researcher decided to take a random sample of students to be interviewed. Two statisticians were consulted regarding the sampling scheme, and their suggestions are illustrated below: Statistician 1 Scheme: From each public university in the state, obtain a list of students who signed-up for Fall classes as of May 2022, and take a random sample of 1000 students per university for interview. Statistician 2 Scheme: Combine the list of students who signed-up for F all classes as of May 2022 obtained from the registrar of each public university and select every 15th student on the combined list for interview. a. Is this an observational or experimental study? Justify your choice. b. What sampling scheme is illustrated using Statistician 1's scheme? c. What sampling scheme is illustrated using Statistician 2's scheme? d. Regardless of the scheme used, the study demonstrates selection bias in obtaining the information. Explain how selection bias is apparent in this study