Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
opt-out of agreement to arbitrate : you can decline this agreement to arbitrate by contacting legal@fitbit.com within 30 days of first accepting these terms of service and stating that you ( include your first and last name ) decline this arbitration agreement . 

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