OG1 阅读 Q19

Choice A is the best answer. The paragraph examines how gift-givers believe expensive gifts are more thoughtful than less expensive gifts and will be more valued by recipients. The work of Camerer and others offers an explanation for the gift-givers' reasoning: "gift-givers attempt to signal their positive attitudes toward the intended recipient and their willingness to invest resources in a future relationship" (lines 57-60,"whereby...elationship").
Choices B, C, and D are incorrect because the theory articulated by Camerer and others is used to explain an idea put forward by the authors ("givers believe that bigger ... gifts convey stronger signals"), not to introduce an argument, question a motive, or support a conclusion.