One Reason That Shift Work Has a Detrimental Effect on Circadian

One reason that shift work has a detrimental effect on circadian rhythms is that:

A) there isn't enough variability in the sleep schedules of shift workers.
B) the nature of shift work is more physically taxing than other types of work typically done during the day.
C) shift workers often get too much sleep.
D) shift workers often go home in the morning daylight,which makes it difficult to properly reset their circadian clocks.