Final answer:
The question about Riley's lack of response to her father's post-argument is not directly addressed in the provided excerpts, making it difficult to determine the precise reason for her silence. It could be due to emotional exhaustion, internal conflicts, or other complex dynamics.
Step-by-step explanation:
The question of why Riley did not respond when her father came to speak with her about the argument could be attributed to a variety of nuanced reasons within the context of the story such as emotional exhaustion, internal conflicts, or a complex relationship dynamic yet to be discussed in the provided excerpts. Without specific reference to a character named Riley or an associated argument in the excerpts provided, it is challenging to interpret her silence accurately. Riley's lack of response may be a narrative device used to showcase tension, underscore a particular theme, or develop her character.