Final answer:
The sentence 'Vosotros se mordéis las uñas.' is NOT grammatically correct in Spanish.
Step-by-step explanation:
In Spanish, reflexive pronouns are used to indicate that the subject of a verb is also its object. The correct form of the reflexive pronoun in the sentence 'Nosotros nos mordemos las uñas.' shows that the subject 'Nosotros' is also the object. The sentence 'Vosotros se mordéis las uñas.' contains a mismatch between the subject 'Vosotros' and the reflexive pronoun 'se'. Therefore, the correct answer is: Vosotros se mordéis las uñas.
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