Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
some cities may require a license to guide tours or to sail . 

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