Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
( f ) to retain a copy , you must either have a printer connected to your personal computer or other device or , alternatively , the ability to save a copy through use of printing service or software such as adobe acrobat ® . 

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