Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
by agreeing to become a member you opt-in to receiving occasional special offer , marketing , survey and product based communication emails . 

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