The correct answer is: D. No error
The sentence is grammatically correct. The subject “Everyone visiting the house” is plural, so the verb “asked” is also plural.
The object of the verb “asked” is “the young girl,” which is singular. The prepositional phrase “how could she kill the wolf” is modifying the verb “asked,” so it is grammatically correct. The prepositional phrase “single handed and without a weapon” is modifying the verb “kill,” so it is also grammatically correct.The sentence could be improved by adding more detail. For example, we could say: “Everyone visiting the house asked the young girl, who had just killed the wolf single-handedly and without a weapon, how she had done it.” This would provide more information about the situation and make the sentence more interesting.