I think the answer should be C or D since there is a twist in the question:"hardly acknowledges the honor of such a distinction." That means the word used to describe the Nobel Prize was inadequate or underwhelming — it failed to properly honor an achievement of that magnitude. So we need two words that sound unremarkable or ordinary, not celebratory — words that would understate rather than elevate the achievement.
C. Plateau suggests a leveling-off or a flat, unremarkable stretch — not a triumphant peak. Calling a Nobel Prize the "plateau" of someone's career undersells it, implying stagnation rather than a crowning achievement.
D. Median means the middle or average point — describing a Nobel Prize as merely the "median" of a career is almost absurdly deflating, treating a career-defining honor as just an average point along the way.