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