Which constitutional amendment guarantees the right to vote in Texas?

The correct choice is the 15th Amendment, which guarantees the right to vote regardless of race, color, or previous condition of servitude. This amendment was ratified in 1870 and was pivotal in addressing racial discrimination in voting. Although it does not specifically pertain to Texas alone, it forms the foundation of voting rights that also apply within the state.

It's important to note that while the other amendments listed address specific aspects of voting rights—such as the 19th Amendment granting women the right to vote, the 24th Amendment prohibiting poll taxes in federal elections, and the 26th Amendment lowering the voting age to 18—none of these collectively guarantee the right to vote in the same fundamental way as the 15th Amendment does by addressing racial discrimination directly. Therefore, the 15th Amendment is central to understanding the legal basis for voting rights in Texas.