In an experiment to examine the effects of sleep deprivation on completion of a puzzle, one group is allowed to sleep eight hours while another group is made to stay awake. in this experiment, the control group is:

I believe the answer is: the group that gets to sleep

Control group refers to the group of subjects that do not receive special treatment. (since normally people allowed to sleep, being told not to sleep is a special treatment). The control group would be used by researchers as a benchmark of measurement during data collection.

answer; the region experienced a surplus of food;