What key provision does the 15th Amendment guarantee?

The 15th Amendment, ratified in 1870, specifically addresses voting rights and ensures that the right to vote cannot be denied or abridged by the United States or any state on account of race, color, or previous condition of servitude. This provision was a significant milestone in the fight for civil rights, as it aimed to secure voting rights for African American men following the Civil War. The amendment sought to eliminate racial discrimination in voting, thus playing a crucial role in the broader struggle for equality and civil rights in the United States.

The other choices do not pertain to the core intent of the 15th Amendment. The prohibition of income tax relates to the 16th Amendment, while the direct election of Senators is established by the 17th Amendment. The concept of separation of church and state does not directly link to voting rights and is more commonly associated with the establishment clause in the First Amendment.