Which word best describes the emotional response to an act of unfairness?

The appropriate choice is the term that specifically captures the emotional response tied to an act deemed unfair, which is "outrage." "Injustice" refers more to the condition or concept of unfairness itself rather than the emotional reaction that follows. When someone perceives an injustice, they commonly feel a strong emotional urgency or anger, which is accurately characterized by "outrage."

In contrast, "fairness" is more about the quality of being just or impartial and does not connect to an emotional response. Similarly, "discontent" reflects a general sense of dissatisfaction but lacks the intensity associated with feelings ignited by a perceived unfairness. Therefore, "outrage" distinctly embodies the immediate emotional response related to witnessing or experiencing an act of unfairness.