They were all members of the Axis Powers. Hope this helps :)
A. a structured test of a hypothesis
there are different steps to an experiment that you follow which prove the hypothesis (or educated guess) right or wrong
Psychology would be best described as the scientific study of behavior and mental processes
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.