Which is an example of a voting requirement that was used to prevent african-americans from voting during the jim crow

I believe that the correct answer is poll tax.
The reason why poll taxes existed at the time was because white people knew it would be difficult for people of color to pay such taxes in order to vote, so it was they way of discriminating against them. Additionally, there were literacy tests that only black people were supposed to take which would determine their eligibility to vote.