The correct answer is D. Victory.
A triumph is a victory, especially a decisive one. It can also refer to a public celebration of a victory.
Joy is a feeling of great pleasure and happiness.
Excitement is a feeling of eagerness and anticipation.
Gain is an increase in wealth, possessions, or status.
In the context of the question, the word “triumph” is most closely associated with the word “victory.” A triumph is a victory, especially a decisive one. It can also refer to a public celebration of a victory. Joy, excitement, and gain are all positive emotions, but they are not as closely associated with victory as triumph is.