The significance of the title "The Fun They Had" by Isaac Asimov primarily highlights the contrast between children's present and past experiences at school. Therefore, the correct answer is:
C) It highlights the contrast between children's present and past experiences at school.
In the story, the main characters, Margie and Tommy, reflect on the old-fashioned way of schooling and express a sense of nostalgia for the past. The title implies a fondness for those previous experiences, emphasizing how different and less enjoyable their current school experience is with technology.