Which Worker Is Most Likely to Have the Greatest Difficulty

Which worker is most likely to have the greatest difficulty with disruptions in their circadian rhythms?

A) John, who works from 3 PM to midnight five nights a week.
B) Joan, who works from midnight to 8 AM five nights a week.
C) Bill, who works from 8 AM to 4 PM seven days a week.
D) Becky, who works from midnight to 8 AM on the weekends and 8 AM to 4 PM on Tuesday, Wednesday, and Thursday.