Answer:
C). His fond recollections emphasize his genuine sincerity.
Step-by-step explanation:
As per the question, the narration in the given excerpt influence Oskar's credibility through 'his fond recollections that emphasize his genuine sincerity.' The description of these recollections('hung a pendulum...prove that the earth rotated') reflected that how sincere Oskar was and established his image as a 'genuine and sincere' and emphasize his pure and positive efforts. Therefore, option C best reflects that how the author uplifts Oskar's credibility.