Final answer:
Sentence 7 foreshadows something bad about to happen.
Step-by-step explanation:
The sentence that foreshadows that something bad is about to happen is Sentence 7. In this sentence, Keiko looks up and sees that the water is moving, swelling up, and picking up speed as it heads toward the beach. This creates a sense of danger and anticipation for the upcoming events.
Learn more about foreshadowing in literature