Which of the following was not a result of the Cuban Missile Crisis?

Which of the following was not a result of the Cuban Missile Crisis?

a. an easing of tensions in the Cold War
b. the opening of the “hot line” between Moscow and Washington
c. a large increase in the number of refugees from Cuba to the United States
d. a treaty between the U.S. and the U.S.S.R. to end nuclear tests in the atmosphere