The sentence requires a word that indicates a reason for the warning, specifically 'for fear that.' 'Lest' is the appropriate word to use in this situation. **Core Concept:** The function of 'lest' to express fear or avoidance. **Correct Answer Analysis:** Option C, 'lest,' correctly expresses the need to avoid something, and fits the context of the sentence. **Incorrect Answer Analysis:** - Option A, 'linguistic,' relates to language and is not relevant in this context. - Option B, 'legitimate,' means lawful or acceptable, not related to the context. - Option D, 'liberal,' means broad-minded, which does not make sense here. **Key takeaway:** 'Lest' indicates a fear or prevention of something.