After reading this stimulus, I identified the first sentence as the conclusion, and you probably did too. However, they had to make it difficult for us by excluding the word "conclusion" from any of the answer choices. So, how else can we describe it? Remember that a conclusion is an argument based on a premise. The premise supports the conclusion.
This example follows a pretty common format. Study = premise Interpretation of study = conclusion
D is the right answer because it describes this relationship without saying "conclusion." It is a statement that is supported by the premise.