Final answer:
The correct sentence that uses dashes is 'As soon as people saw them—there was panic.' Here, the dash is used correctly to separate two related thoughts.
Step-by-step explanation:
The student asked which sentence uses dashes correctly. Dashes can be used to create emphasis or indicate an abrupt change in thought in a sentence. The key to using dashes correctly is to place them correctly in the sentence by adding a space on both sides, and they should be used to separate a phrase from the rest of the sentence. The correct sentence from the given options is: Option 3: as soon as people saw them—there was panic. In this sentence, the dash creates suspense, separating two related thoughts.
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