Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
portions of tripadvisor mobile software may use copyrighted material , the use of which tripadvisor acknowledges . 

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. OPTIONS: ["Choice of law", "Arbitration", "None", "Content removal", "Jurisdiction", "Unilateral termination", "Unilateral change", "Limitation of liability", "Contract by using"].