单选题 The synergy of humans, society and machines is the fundmental cause of the unparalleled material prosperity of many nations.
A. unpopular B. unpredictable
C. unquestionable D. unprecedented

【正确答案】 D
【答案解析】unpopular：不流行的；unpredictable：不可预测的；unquestionable：无可非议的；unprecedented：空前的。题中unparalleled意为“空前的”，故可知D选项最符合要求。