Question

what caused relations to deteriorate between the united states and the soviet union in 1979?
the united states invaded afghanistan.
the soviet union invaded afghanistan.
the soviet union hosted the olympic games.
the united states ratified the salt ii treaty.

Explanation:

In 1979, the Soviet Union's military invasion of Afghanistan led to a sharp deterioration in US-Soviet relations, prompting the US to take punitive actions like a boycott of the 1980 Moscow Olympics. The other options are incorrect: the US did not invade Afghanistan in 1979, the 1980 Moscow Olympics (hosted by the USSR) were a consequence of the deteriorated relations, and the US never ratified the SALT II Treaty.

Answer:

B. The Soviet Union invaded Afghanistan.