Answer:
This sentence gives him permission to demand his right to vote, a proper education, and proper equality.
Step-by-step explanation:
In his book titled 'The Souls of Black Folk'. W. E. B. DuBois writes about the lives of African American in American society. It is an autobiographical account of DuBois.
In Chapter 3 of the book, DuBois comments on Booker T. Washington who has given up to take the responsibility of speaking for rights of African Americans being from 'thinking classes.'
Therefore, the sentence 'thinking classess of American Negroes' gives DuBois permission to demand for their rights to vote, a proper education, and proper equality.