The correct answer is D ( African Americans ).
Literacy tests asses a person's literacy skills : the ability to read and write.
In the United States, literacy tests were administered to prospective voters in an attempt to drive minorities out of politics ( 1850-1960).
Many states required potential voters to pass literacy tests in order to be allowed to vote. This was a tool designed to deny the voting rights to many poor, uneducated African Americans. Literacy tests, poll taxes and residency restriction were some of the measures used to make sure African American were not allowed to vote, thus not participating in the country's politics.