Final answer:
Valentine's reference to Daniel interpreting the king's dreams is an allusion to the Bible, which is a literary device that indirectly references other works or figures to deepen the understanding of the text.
Step-by-step explanation:
When Valentine tells Graff she cannot help him with Ender, she references Daniel interpreting the king's dreams. This reference is an example of an allusion to the Bible. Allusions are literary devices that reference another work of literature, person, or event without explicitly mentioning it. In this context, Valentine is drawing a parallel between herself and the biblical figure of Daniel, suggesting that similar to how Daniel interpreted dreams for the King, she is being asked to interpret or understand Ender for Graff. This type of allusion is used in literature to create depth and resonance with other texts, ideas, or historical figures, enhancing the reader's understanding of the character's role or situation.