Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
if you engage in any exercise program you receive or learn about through the fitbit service , you agree that you do so at your own risk and are voluntarily participating in these activities . 

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