What is the act of calming someone's anger through concessions?

The act of calming someone's anger through concessions is referred to as "placate." This term specifically describes the process of pacifying or soothing someone who is upset by making compromises or offering concessions. When you placate someone, you are actively working to reduce their anger or dissatisfaction by acknowledging their feelings and perhaps giving in to some of their demands. Such behavior is often seen in conflict resolution, where the goal is to restore peace and understanding in a tense situation.

In contrast, the other options do not relate to this meaning. "Pine" refers to a longing or yearning for something, "plummet" means to fall or drop suddenly, and "pompous" describes someone who is self-important or arrogant. None of these options involve the concept of calming anger through concessions, making "placate" the only suitable choice.