Which amendment grants the right to vote regardless of sex?

The 19th Amendment is significant because it explicitly grants the right to vote to women, removing any limitations based on sex. Ratified in 1920, this amendment marked a pivotal moment in the women's suffrage movement, affirming that individuals cannot be denied the right to vote based solely on their gender.

The other amendments listed do contribute to voting rights but address different aspects. The 15th Amendment prohibits voting discrimination based on race, color, or previous condition of servitude, while the 21st Amendment is related to the repeal of Prohibition. The 26th Amendment lowers the voting age to 18 years but does not address issues of gender. Thus, the 19th Amendment is the correct choice for ensuring voting rights irrespective of sex.