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