考慮

長年の功績を ___ して、彼に特別賞が贈られた。

The correct answer is 「考慮」(こうりょ), meaning "consideration" or "taking into account." The sentence states that a special award was given to him for his "長年の功績" (long years of achievement), implying that these achievements were *considered* or *taken into account* when deciding to give the award. 「危惧」(きぐ) means "fear" or "apprehension"; one does not fear achievements when giving an award. 「発揮」(はっき) means "demonstration" or "display"; one demonstrates one's own abilities, not the achievements of others when giving an award. 「妥協」(だきょう) means "compromise"; compromising on achievements for an award doesn't make sense in this context.

正解は「考慮（こうりょ）」です。「長年の功績」を「考慮」して、つまり「その功績を鑑みて」特別賞が贈られた、という意味に最も合います。「危惧」は心配すること、「発揮」は能力などを出し切ること、「妥協」は譲り合うことで、いずれも文脈に合いません。