The Twenty-Sixth Amendment to the US Constitution, ratified during the Vietnam War,

A. resulted in the removal of US troops from Vietnam.

B. limited the power of the president to commit US forces.

C. repealed the Gulf of Tonkin Resolution.

D. lowered the voting age to eighteen.

D. The 26th amendment lowered the voting age to eighteen. This occurred for many reasons, but the most prominent one was the Vietnam War, which saw the drafting of many soldiers who weren't even old enough to vote for the politicians who were sending them to war, in some cases, against their will. This amendment was meant to address that iniquity.