Answer:
D) To highlight how different birthdays feel.
Step-by-step explanation:
In this passage, the author introduces a flashback. Flashback refers to an interruption in the narrative that a writer uses in order to introduce past events. This is done in order to provide background or context to the current events of a narrative. In this example, the flashback also serves as a way to compare the different birthdays that the character has had. In doing so, we learn more about him, and about the expectations he might have for his birthday.