In a Study of the Effect of Fatigue on Task

Multiple Choice

In a study of the effect of fatigue on task performance,participants were asked to complete a series of puzzles.One day,all participants completed puzzles after 24 hours without sleep.On another day,the same participants completed puzzles after sleeping for at least eight hours.What research design is used in this study

A)  between-subjects design 
B)  within-subjects design 
C)  single-blind design 
D)  interaction design