Which of the following voting rules was based upon an individual African American's family history?

A. Separate voting boxes

B. Poll taxes

C. Grandfather clauses

D. Literacy tests

The 15th Amendment prohibited explicit disenfranchisement on the basis of race or prior ... Starting in 1877, when Georgia passed the cumulative poll tax, states ... for their refusal to receive and count the vote of a black elector in a city election ... of the literacy tests, since some of the understanding and grandfather clauses.

I think the answer is D but not 100% sure