An establishing operation is any change in the environment whicH.

A: momentarily alters the effectiveness of the consequence for a behavior that was previously followed by reinforcement. B: alters the timing of a behavior and momentarily alters the frequency of the behavior that was previously followed by reinforcement. C: alters the effectiveness of some object or event as reinforcement thus momentarily changing the likelihood of behavior that was previously followed by that reinforcer. D: alters the effectiveness of some object or event as a contingency-shaped rule and at the same time changes the momentary frequency of the behavior that was previously followed by reinforcement.