What term was given to the lessening of tensions between the united states and the soviet union during the 1960s and 1970s? a. perestroika b. the united nations c. the bipolar agreement d. detente

 D. Detente

Détente means "loosening" or "relaxing."  Countries which have been strongly at odds with one another, with much tension between them, make an effort to relax that tension through negotiations.   

In history, the famous example of détente occurred between the USA and the USSR, especially in the 1970s.  There was an effort to ease the heated tensions of the Cold War.  Rather than continuing the massive buildup of nuclear arsenals in an arms race, the United States and the Soviet Union began to talk to one another about the strategic reduction of armaments. The nations' leaders, Leonid Brezhnev and Richard Nixon, met in Moscow in 1972 -- the first visit of a US president to Moscow.  They signed agreements stemming from these Strategic Arms Limitations Talks (SALT), which began a new direction in policy between the two superpowers.

d) iowa i believe is the answer