Question

following the passage of the fifteenth amendment, states attempted to limit voting rights of african americans through
registration quotas.
state constitutions.
poll taxes and literacy tests.
blood tests and genealogy.

Explanation:

After the Fifteenth Amendment (which prohibited the denial of the right to vote based on race, color, or previous condition of servitude), states used poll taxes (a fee to vote) and literacy tests (tests to determine if one could read) as discriminatory measures. Registration quotas were not a common method. State constitutions were not the main tool here. Blood tests and genealogy were not relevant to limiting voting rights post - Fifteenth Amendment.

Answer:

poll taxes and literacy tests.