The policy of striking a nation that might be contemplating hostile actions is called

A) diplomacy.
B) appeasement.
C) détente.
D) preventive war.

Preventive war refers to the policy of initiating a military strike against a nation that may potentially pose a threat to one's own nation's security, often based on intelligence or perceived risk. This policy is aimed at preventing potential attacks or aggression from the other party, but is controversial because it can lead to unnecessary or unjustified wars. Diplomacy and détente are policies that involve negotiations and peace efforts, while appeasement refers to the policy of making concessions to a potentially hostile nation to avoid conflict.