Which of the following is true of the employment of Black women?

a$.$

Research suggests that Black women are preferred by employers over White women and Black men.

b$.$

Black women earn more than Black men.

c$.$

White, Asian, and Native American women in the U$.$S$.$ are more likely to work outside the home than Black women.

d$.$

Black women who work for unionized firms earn nearly $40\%$ more than Black women who work for nonunionized firms.