Final answer:
The correct sentence that uses a dash correctly is option b) "She bought flowers, chocolates, and cards - for everyone."
Step-by-step explanation:
The correct sentence that uses a dash correctly is option b) "She bought flowers, chocolates, and cards - for everyone." A dash can be used to set off a phrase for emphasis or to indicate a pause or interruption in the sentence. In this sentence, the dash is used to set off the phrase "for everyone" to emphasize the fact that she bought the items for everyone.