She remains confident and ______untroubled by our present problems.

A．the inconveniences brought about to the workers by the introduction of automation
B．the disturbance of the daily life cycle of workers who have to change shifts too frequently
C．the fact that people working at night are often less effective
D．the fact that it is difficult to find a number of good night workers

A．body temperature changes when the cycle of sleep and wakefulness alternates
B．body temperature changes when he changes to night shift or back
C．the temperature reverses when the routine is changed
D．people have higher temperatures when they are working efficiently