Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
when you use the fitbit service after a modification becomes effective , you are telling us that you accept the modified terms . 

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