Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
any personal data obtained from children and parents during contests will be kept until the contest ends and prizes are delivered , and then it will be deleted . 

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