Answer:
B) Laughing uproariously, the little girls ran away from the group of boys they'd just attacked with water balloons.
Step-by-step explanation:
Participle phrases work as adjectives: they start with -ing if it is a present participle, and they begin with a past participle form if it refers to the past. In this case, the participle phrase is laughing uproariously, which provides characterization to the sentence.