The correct answer is D.
Détente is a term used in international affairs to refer to a strategy that consists on easing previously tense relationships.
The détente policy adopted by president Nixon in the 1970s, aimed to improve the relationships between the URSS, and the Western bloc of capitalist countries leaded by the URSS. After that, when obvious weaknesses sent president Nixon out of office, the URSS took the opportunity and tried to expand its influence by attempting to invade Afganistan in 1979, which finally ended detente intentions.