The statement "The argument is valid because Du Bois gives relevant reasons to support his claim" best explains the validity of this argument. In the passage, Du Bois presents a clear argument about the triple paradox of Booker T. Washington's career, and he supports his claim by providing specific reasons and evidence to illustrate each paradox. He argues that Washington's goals of promoting black economic advancement and self-reliance are undermined by his acceptance of second-class citizenship and lack of support for higher education, and he provides evidence to support these claims. Therefore, the argument is valid because it presents a clear and logical argument with supporting evidence.