Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
children under thirteen ( 13 ) years of age are allowed to participate in contests . 

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