The Main Reason for the Movement of Women into Male-Dominated

The main reason for the movement of women into male-dominated occupations and the lack of movement of men into female-dominated occupations is

A) lack of training for men to perform the jobs that women typically occupy.
B) lack of economic motivation for men to seek women's jobs.
C) oversupply of women in the workforce, which has motivated women to seek jobs traditionally occupied by men.
D) lack of qualified workers of both genders.