Which amendment describes who can vote?

The amendment that specifies that citizens who are 18 years of age and older can vote is the 26th Amendment to the United States Constitution. Ratified in 1971, this amendment was a significant step in expanding voting rights by ensuring that young adults, particularly those who were being drafted into military service during the Vietnam War, were able to exercise their right to vote. This change recognized that age should not be a barrier to participating in the democratic process.

The other options pertain to different amendments or laws but do not solely focus on the age requirement for voting. The argument for all citizens regardless of race relates to the 15th Amendment, which prohibits voting discrimination based on race. The right of women to vote is addressed in the 19th Amendment, which extends voting rights to women. Finally, the requirement of paying a poll tax was eliminated by the 24th Amendment, which removed financial barriers to voting. Thus, option A is the only one that directly addresses the age criteria for voting.