President thieu
a) resigned two weeks after the paris peace accords
b) observed the cease-fire established by the paris peace accords
c) promised north vietnam billions of dollars in postwar reconstruction aid
d) counted on nixon's pledges of support to save south vietnam

D) counted on Nixon's pledges of support to save South Vietnam

Explanation:

President Thieu was the general in the army of the Republic of Vietnam. He became the general after the coup against Ngo Dinh Diem. In 1972, a war occurred between South and North Vietnam. After many days of the bombing, both countries were called upon to sign a peace treaty. But the North didn’t agree with what the South proposed and the war continued. Both countries then meet again to sign the treaty. Thieu refused to sign the peace treaty this time but Nixon promised to come to the aid of South Vietnam if the communists violated the terms of the peace treaty, and Thieu agreed to sign  

i believe the answer is c