What was the control group in this study? a) The group that flew an equal amount of time distance but crossed no time zones
b )None of these
c) The researchers conducting the study
d) The group that crossed the most time zones

a) The group that flew an equal amount of time distance but crossed no time zones

Explanation:

A "control group" refers to a particular group in a research study that becomes the basis for observing the changes in other groups. This group is not subjected to any experimental treatment.

In the question above, choice A is the control group because it wasn't subjected to different time zones. This group will be compared to those groups that crossed the different time zones. This group is important in the study in order to make sure that the experiment is valid.