Answer:
immediately before the unconditioned stimulus.
Explanation:
The theory of the classical conditioning explained how a certain behavior or response can be obtained from pairing unconditioned stimulus and conditioned stimulus. The timing of the pairing should be given considerable importance. The conditioned stimulus should be either used before or during the unconditioned stimulus and therefore it should serve as a cue to it. And the result would be a conditioned stimulus would produce a conditioned response.
