People who have gone without sleep for 10 days in a row

A) have lost all muscle coordination.
B) can still perform well-practiced skills for brief periods.
C) feel equally sleepy at all times of the day.
D) experience unpleasant aftereffects even weeks or months after returning to a normal schedule.

Research suggests that even after 10 days of sleep deprivation, people can still perform well-practiced skills for brief periods. However, their overall cognitive ability and decision-making skills are severely diminished. A, C, and D are untrue statements; they may experience muscle fatigue, but not to the point of losing all muscle coordination. They tend to feel sleepier during certain times of the day (usually mid-afternoon and late at night). And although they may experience unpleasant aftereffects, they typically resolve within a few days to a few weeks, unlike the long-term effects mentioned in statement D.