If Someone Is Placed in a Dark Cave or Room

If someone is placed in a dark cave or room where they are not exposed to the changing light conditions of night and day, what will happen to them if they stay there for a prolonged period of time?

A) They will tend to get up at roughly the same time each day.
B) They will tend to get up earlier and earlier each day.
C) They will tend to get up earlier but go to bed later each day.
D) They will tend to get up later and later each day.