Explanation
Correct answer: D.
Choice D is the best answer. The text describes a study assessing how children think of rewards and fairness and its results. It concludes that the children in the study may have thought that a teacher who counted out loud when giving rewards cared more about fairness than a teacher who did not count out loud.
Why the other choices are wrong
Choice A
Choice A is incorrect. The children in the study are described as being “four to six,” and the text doesn’t mention any differences among the different ages.
Choice B
Choice B is incorrect. The experiment wasn’t about teaching math—rather, it was about how counting out loud affected the children’s perception of fairness.
Choice C
Choice C is incorrect. The experiment doesn’t focus on whether the children care about fairness, and the text never mentions the children’s expectations of being rewarded.