Which of the Following Is a Major Difference Between Levinson's

Which of the following is a major difference between Levinson's and Vaillant's views on midlife?

A) Unlike Vaillant, Levinson 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.