Final answer:
The researcher should use a Latin Square design to compare the different types of college courses and control for the student's GPA.
Step-by-step explanation:
The researcher should use a (b) Latin Square design.
A Latin Square design is appropriate for this study because it allows the researcher to control for the student's GPA while also comparing the different types of courses. The Latin Square design ensures that each combination of course type and student's GPA is represented in a balanced and systematic way, reducing the potential for confounding variables.
In this design, each row represents a student's GPA level, each column represents a course type, and each cell represents a specific combination of GPA and course type. This design minimizes the effect of individual differences in GPA on the overall course average, allowing the researcher to focus on the differences between course types.