Hi, let's start with how the two authors actually use the study in question. The first author sets out their thesis, which is more or less that habituation and rivalry cause people not to be happy with their income unless it's increasing relative to their peers. The author then uses the study to show that rivalry does indeed happen.
The second author treats the study as the jumping off point for their discussion of what it means, and then eventually settles on the somewhat counterintuitive main point that the study actually reveals something quite positive.
Since both D and C share the same description of A, let's ignore that and focus on B. I think the main issue with C is that I don't think the study presents the view that the author is supporting, but rather, is evidence meant to introduce the authors overall subject matter. The author also doesn't present any more evidence that the experiment is correct, but rather the author presents evidence that help us to contextualize and understand the results of the study.
