Research on Using Massed and Spaced Practice to Train Postal

Research on using massed and spaced practice to train postal workers to use a letter-sorting machine showed that:

A) the group that was the most satisfied with the training process also learned it the most quickly.
B) those using spaced practice were more satisfied with their training.
C) those using massed practice required the fewest hours of training to learn the task.
D) those using spaced practice required the fewest hours of training to learn the task.