C: His fond recollections emphasize his genuine sincerity.
In the excerpt the narrator remembers different things that they used to do in his dad's closet. He talks about how they'd wrestle, tell jokes, and hung a pendulum. The other options are easily eliminated. A is wrong because using the adjective Greco-Roman is not enough of a reference to indicate someone is intellingent. B is wrong because it hanging a pendulum does not indicate maturity. Option D is wrong because he doesn't describe his dad at all, just things they used to do in his dad's closet.