The right answer is North Vietnam agreed to peace treaty with US.
During 1972, the mounting social divisions at home and the approach of the presidential election influenced the stalled negotiations in Paris between the United States and representatives of North Vietnam. The Paris peace talks broke off on December 16, and two days later the newly reelected Nixon ordered massive bombing of Hanoi and Haiphong, the two largest cities in North Vietnam. On January 27, 1973, the United States, North and South Vietnam, and the Viet Cong signed an “agreement on ending the war and restoring peace in Vietnam.”