Final answer:
Barriers to career promotion contribute to the income gap between black and white men, along with differences in education levels and discrimination.
Step-by-step explanation:
Barriers to career promotion account for part of the income gap between black and white men. The remaining racial gap in earnings can be attributed to continuing differences in education levels and the presence of discrimination. Studies have shown that black workers, particularly those with lower levels of education, earn lower wages compared to their white counterparts. This suggests that barriers to career advancement, such as limited access to educational opportunities and discrimination in job opportunities, contribute to the income gap between black and white men.