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 . 

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