Hi Shaela! Thanks so much for your great question.
Yes, this question is a Justify the Conclusion question. On Justify questions, we want to use the Justify Formula (Premises + Answer Choice = Conclusion) to figure out what piece of information, when added to the premises, will make the argument valid.
In other words, for this question, we want to identify what the gap is between the premises and the conclusion. The argument is structured as follows:
Premise 1: Some managers think competition among employees will maximize their performance
Premise 2: If there is one competitor who seems clearly superior, the others will become anxious and doubt their abilities
Conclusion: Stiff competition can undermine its goal of maximizing employee performance
In this argument, the gap is that we don't know that some employees becoming anxious and doubting their abilities will prevent maximizing employee performance. When looking through the answer choices, we can expect that one of them will fill this gap and connect becoming anxious/doubting one's abilities with poor employee performance.
Answer choice (D) fills this precise gap. To your question about the term "overall performance," it's not an issue that the answer choice discusses "overall performance" since "overall performance" would also encompass "employee performance."
Answer choice (C) does not fill the gap that we saw in the argument. First, it mentions competitors perceiving the competition as winnable, but nothing in the stimulus discusses this concept of winnable. Second, the answer choice discusses overall performance improving, but we want to connect the situation to decreasing overall performance since the conclusion is about undermining the goal of maximizing employee performance.
I hope this helps, and let me know if I can clarify further