Professor Frohardt Is Interested in Studying Endogenous Circadian Rhythms

Professor Frohardt is interested in studying endogenous circadian rhythms.Which of the following is a research design that would allow him to conduct his study most effectively?

A) Force subjects to follow a strict sleeping-working-eating schedule.
B) Conduct an experiment in open spaces with many external cues.
C) Have participants live in caves,mines,or specially prepared rooms.
D) Use statistical comparisons between groups with and without endogenous body rhythms.