#GRE#填空：动名词的题目怎么解？与主语动作一致

Asserting a need to preserve the ___ that became the hallmark of her predecessor's tenure, the new director of federal monetary policy refused to subscribe to rigid or mechanistic rules in policy making. 主张保持一种她前任任期的标志的[灵活性]，新任财政部长她拒绝同意政策制定时的过于刻板或机械的规则。