Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
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except for such updated terms , this agreement may not be modified except by mutual written agreement between you and linden lab that is signed by hand ( not electronically ) by duly authorized representatives of both parties and expressly references amendment of this agreement . 

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