How do I know which category would be the correct ones on a word problem about surveys, studyies, and experiments?

Julie is an education researcher interested in understanding the effects of tutoring on student performance. There are many ways she could study this question. Match each research method with a description of how Julie could conduct this study. l SUWEY H. Without interacting with any students, Julie randomly selects 20 students from a tutoring program and 20 students not in a tutoring program. She then looks up their grades in the student records. Julie randomly assigns a sample of students to receive tutoring assistanoe or a control condition where they do not receive tutoring. She then examines changes in student grades at the beginning of the study vs. three months later. Julie sends out a questionnaire to ask students whether they have used a tutor. The questionnaire also asks students to rate how well they are doing in school on a scale from 1 (not very well) to 10 (very well). :: Julie does not collect her own data. Instead, she looks up previous research studies on tutoring programs and evaluates whether they were effective