Answer: The correct answer is : Contingency
Explanation: In behaviorism contingency is explained as the association that exists between two occurrences or events, one being "contingent" or the consequence of the other. For classical conditioning to occur, elements of the said system must be contingent with each other, a conditioned stimulus must precede the unconditioned stimuli closely in time, and it also must serve as a reliable indicator that the unconditioned stimulus is on its way.
In conclusion, the correct answer is Contingency.
