单选题 According to the passage, why do people join groups that practice secondary cooperation?

A、 To share the happiness with others.
B、 To get rewards for themselves.
C、 To associate with people who have similar backgrounds.
D、 To defeat a common enemy.

【正确答案】 B

【答案解析】[分析] 推断题型。见第三段倒数第二句：Members perform tasks so that they can separately enjoy the fruits of their cooperation in the form of salary，prestige，or power．加入第二级合作的小组成员完成任务的目的是他们均能分别享受到合作的成果；而这种成果是以薪水、威望和权利的形式体现的。由此可推断出选项B是正确答案。