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