which best describes the conclusion of U.S involvement in vietnam

the vietnam war drags on and anti-war protests increase; president nixon begins pulling out american troops; south vietnam falls to the communist north

president nixon escalates american ground troops in vietnam; with the help of the south vietnamese troops, U.S defeats the communist north

north vietnam quickly defeats the U.S, forcing american troops out of vietnam

the U.S stays in vietnam until the south vietnamese can push back the viet cong into north vietnam. North and south vietnam stay divided after a cease-fire is signed