Final answer:
Nick Carraway in F. Scott Fitzgerald's novel believes temperance is one of his virtues, and textual evidence from the narrative supports this claim through his moderate and self-contained demeanor in the midst of the extravagant lifestyle presented.
Step-by-step explanation:
At the end of chapter 3 in F. Scott Fitzgerald's novel, Nick Carraway alludes to what he believes is "one of the cardinal virtues" he possesses. In context, this virtue can be identified as temperance. This assertion by Nick can be supported by textual evidence from the novel itself, where Nick's character is generally presented as more reserved and controlled compared to the other characters, particularly in the lavish and often excessive world of Jay Gatsby. For instance, although he attends Gatsby's opulent parties, he does so as an observer rather than a participant fully indulging in the hedonistic lifestyle. The Great Gatsby often contrasts Nick's relative moderation and self-restraint with the extravagant and reckless behavior of those around him, thus supporting the idea that temperance is indeed a virtue that he maintains.