S1 문장의 [______]에 들어갈 단어는?

난이도 고난도 · 힌트를 덜 열수록 높은 점수 (현재 5점)
Gold plating in the project means needlessly enhancing the expected results, namely, adding characteristics that are [______], not required, and that have low added value with respect to the targets ― in other words, giving more with no real justification other than to demonstrate one's own talent.