A Variable-Ratio Schedule Is Difficult to Use for Formal Rewards

A variable-ratio schedule is difficult to use for formal rewards such as pay because:

A) it typically weakens the behavior that has been previously rewarded.
B) is the least powerful schedule in terms of maintaining the desired behaviors.
C) it has a fixed number of desires to needed for each reinforcement.
D) it does not motivate the employee to increase the frequency of the desired behavior.
E) it would be complicated to keep track of who was rewarded when.