Concept:This sentence expresses an unreal past condition in an inverted form.Explanation:The phrase "Had she told me" is equivalent to "If she had told me."When such a past perfect condition is used, the main clause must take "would have + past participle."Among the options, only "would have stopped" fits this pattern.So the completed sentence is: "Had she told me, I would have stopped you."Answer:B. would have stopped