A、Having a point. B、Having flexibility. C、Making sense. D、Being interesting. C短文中提到，有意义的工作包含3个关键要素。第1个要素是工作必须要讲得通，个人必须了解自己的工作任务，

Three men are found smashing boulders with iron hammers. When asked what they are doing, the first man says, "Breaking big rocks into little rocks." [20]The second man says, "Feeding my family." The third man says, "Building a cathedral."
    Today’s column focuses on the third man, the one who saw each hammer blow as contributing to the construction of a cathedral, a home for human dreams and sacred aspirations. To many of us who study and consult in occupational and organizational contexts, we would call what this third man does meaningful work.
    [21]I have come to see meaningful work as consisting of three central components. First, the work we do must make sense; we must know what’s being asked of us and be able to identify the personal or organizational resources we need to do our job. Second, the work we do must have a point; we must be able to see how the little tasks we engage in build, brick-by-brick if you will, into an important part of the purpose of our company. Finally, the work that we do must benefit some greater good; we must be able to see how our toil helps others, whether that’s saving the planet, saving a life, or making our co-workers’ jobs easier so that they can go home and really be available for their families and friends. [22]A growing body of evidence shows that meaningful workers are happy workers, more committed workers, and, in some tantalizing ways, better workers.
20. What does the second man answer when asked what they are doing?
21. According to the speaker, what is the first central component of a meaningful work?
22. What does the growing body of evidence show?