This text is mainly about ______.

答案：[B] approaches to getting more done in less time.

解析：根据题目的mainly about可知为文章主旨题，首先可以通过题目的复现内容找与文章主旨有关的词汇。题目中反复出现了focus，可判断与人们的注意力有关。其次，文章主旨一般在开篇第一段或第二段出现，第一段引用Cal Newport的观点提出focus without distraction话题，第二段就提到了主题approaches to mastering the art of deep work，此刻主题已明确，并且第四段有明显的证明another approach。所以本题选B. approaches to getting more done in less time。