Which of the following is a major difference between Levinson's and Vaillant's views on midlife? A) Unlike VaillantLevinson believes that only males experience a midlife crisis. B) Unlike Levinson, Vaillant maintains that only a minority of adults experience a midlife crisis C) Levinson maintains that the transition period to midlife is 6 years, while Vaillant holds it to be 8 years D) Unlike Levinson, Vaillant's study was mainly focused on white, middle-aged, male population within the upper SES of society.