Which line from Extremely Loud and Incredibly Close reveals a nostalgic tone?

The correct answer for the question that is being presented above is this one: " d. We used to Greco-Roman wrestle on the floor in there, and tell hilarious jokes, and once we hung a pendulum from the ceiling and put a circle of dominoes on the floor to prove that the earth rotated."

d. We used to Greco-Roman wrestle on the floor in there, and tell hilarious jokes, and once we hung a pendulum from the ceiling and put a circle of dominoes on the floor to prove that the earth rotated.

The thing to remember about nostalgia is that if writing/text is nostalgic, it will always be discussing the past as a memory of a time in which the speaker/writer seems to long for, the thought of which brings a sadness because the time being described is gone. Thus, nostalgia is bittersweet because of how a good memories bring sadness.