Final answer:
The 24th Amendment limited states' rights to determine voter qualifications by banning poll taxes in federal elections. The correct answer is option 4.
Step-by-step explanation:
The constitutional right of the states to determine the qualifications for voting was most directly limited by the 24th Amendment. The 24th Amendment, ratified in 1964, specifically banned poll taxes in elections for federal office, which had previously served as a barrier to voting for many low-income individuals, particularly African Americans in the South. While the Thirteenth Amendment abolished slavery and the Civil Rights Act of 1964 addressed a wide range of discriminatory practices, it was the 24th Amendment that directly addressed and prohibited one of the financial barriers to voting. Further protection was provided by the Voting Rights Act of 1965, which enforced the voting rights guaranteed by the 15th Amendment, especially in areas with a history of discriminatory practices.