Choose the closest paraphrased version after the following sentence or the italicized part.
It is rather the most disturbing element in civilization, the most profoundly revolutionary thing which has ever been let loose in the world.（ ）
A、
...the revolution that human race is not ready to welcome.
B、
...the greatest challenge that mankind has ever had to meet.
C、
...the unexpected thing that takes some time for people to accept.
D、
...the new inventions that people in the modern world are facing.
【正确答案】：B
【题目解析】：
句子释义：…是世上迄今所爆发的最深刻的革命事件。此处强调的是“最深刻的革命事件”。
B选项“…人类迄今为止所必须面对的最大的挑战”，“革命事件”与“挑战”含义相近，符合题意。