Which aspect of American culture in the late 19th century was a major cause a
of the "plexus of social problems" that W. E. B. Du Bois refers to in 'The Study
of the Negro Problems"?

A. Racial segregation resulted in African Americans being denied
educational opportunities that were available to white students.

B. Low self-esteem among African Americans kept them from pursuing the careers that were available to them.

C. African Americans struggled to adjust to political freedom and
continued to vote for politicians who ignored their interests.

D. During the Civil War, several regiments of the Union Army
consisted of only African American soldiers.