A stimulus for which there is no conditioned response is called a unconditioned stimulus. The unconditioned stimulus is a<span> stimulus that naturally and automatically provokes and triggers a behavior or response.</span><span>During the process of classical conditioning, the neutral stimulus (NS) is converted into the unconditioned stimulus.</span>
C, A, A, C, hope this helps
The answer is: positive relationship
Reference period refers to the amount of time that has passed after the data for statistical report occurs. As the reference period increase, its more likely that the record that contain the data is already missing or forgotten, which correlate positively to the number of under reporting.
