Answer:
D
Step-by-step explanation:
Since the study was to find out the effectiveness of online courses, the appropriate research question that will guide the investigation would be 'Which courses have better exam scores online or traditional ?'.
In order to investigate the effectiveness, it would be important to know how students perform in online courses as compared to the traditional versions of the same courses. The comparison of the two performances would give a good insight into the effectiveness of online courses.