Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
( a ) you may sign up as a registered user of the products free of charge ( a `` member '' ) . 

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