Continuing the setup from the prior item] Suppose that six students in a POL 138 quantitative reasoning course take a final exam. The instructor is interested in whether attending class increased student scores on the final exam, but the instructor realizes that students who attend class might on average have been better or worse at quantitative reasoning even before the POL 138 course started, so the instructor uses a student's pretest score as a control in the analysis. Data from the students are in the table below. The first column indicates whether the student attended each class, the middle column indicates the student's pretest score, and the third column indicates the student's final exam score:

Full Pretest Final Attend? Score Score ------------------------ No 2 20 No 2 20 No 6 60 Yes 2 50 Yes 6 90 Yes 6 90

Based on the table data, statistical control for a student's pretest score makes full attendance seem ___ at improving a student's final exam score, compared to an analysis of the data without any statistical control.

Group of answer choices

A. less effective

B. as effective

C. more effective