A substantial hike in the top rate of income tax would not solve this problem but merely aggravate the nation' s already waning support.

【正确答案】 C

【答案解析】解析：句意：大量增加所得税的最高税率不能解决问题，而仅仅会恶化人们对国家本已欠缺的支持。wane衰退，减弱。decline下降。depreciate贬低，降职。warn警告，通知。startle震惊。