Which of the following statements concerning culture-fair tests is TRUE? a. Psychologists have been unsuccessful in developing such tests to reliably compare people from different cultures. b. Although culture-fair tests exist, they are very expensive to administer and are therefore less popular than culture-specific tests. c. Psychologists have successfully developed a number of such tests that reliably compare people from different cultures. d. The use of culture-fair tests have revealed that the intelligence gap between majority and minority groups is even larger than once believed.