Classical conditioning is most successful when the neutral stimulus begins: long before the unconditioned stimulus begins. immediately after the unconditioned stimulus begins. just before the unconditioned stimulus begins. x at exactly the same time that the unconditioned stimulus begins.

I believe the answer is: just before the unconditioned stimulus begins.

By pairing the neutral stimulus with unconditioned stimulus on a short period of time, the subject would automatically perceive that both of them are strongly correlated.  This speed up the creation of conditioned response that intended toward the subjects,.

answer; i do believe that its(gestation,suction-aspiration or vacuum aspiration;