Dr Franke Is Conducting an Experiment on Group Decision Making

Multiple Choice

Dr. Franke is conducting an experiment on group decision making. The experiment will run for an entire academic semester. Dr. Franke runs his experimental group at the beginning of the semester and his control group at the end of the semester. The confounding variable here is:

A) that different groups were run at different times during the semester.
B) not including more than one control group.
C) choosing to run his experiment at an academic institution.
D) None of the answers is correct.