Question: Two researchers are interested in studying the relationship between college grades (GPA) and reasoning ability. Researcher A gives a specially designed reasoning test to the 40 students with the highest GPA and the 40 students with the lowest GPA in a class of 1000 second-year students. Researcher B gives the same test to 80 students chosen at random from the same second-year class. Which researcher can be expected to obtain the highest correlation between GPA and the reasoning test? Which correlation is the more appropriate for this study? Why?