Final answer:
The correct answer is B. detente, which is a policy of reducing tensions between superpowers, especially during the Cold War, to prevent nuclear war and promote stability.
Step-by-step explanation:
The policy defined as "easing of tension" that helped alleviate the threat of nuclear war among the superpowers during the Cold War is B. detente.
Detente refers to the reduction of tensions between adversaries, particularly between political leaders and nations. During the Cold War, detente was a significant shift from previous policies that had heightened the risk of nuclear confrontation. Instead of continuing policies like brinkmanship, which pushed the superpowers to the verge of war, detente sought to avoid conflict and promote understanding.
This was partially achieved by arms control agreements, diplomatic efforts, and recognition that policies directed at containment of the opposing ideology should not lead to mutual destruction. Although there were differing opinions about the effectiveness and intentions behind detente, it generally represented an attempt to bring about a more peaceful and stable international environment. The concept acknowledges that while the superpowers had divergent interests, they shared a common interest in avoiding a nuclear catastrophe.