单选题 The pioneers' greatest asset was not their material wealth but their ______.
【正确答案】 A
【答案解析】(fortitude坚忍，刚毅)。句意为：开拓者们的最大财富不是他们的物质财富而是他们坚韧不拔的精神。B．simplicity朴素；C．companions伴侣；D．possessions财产。