EU antitrust regulators want to know whether LinkedIn’s data is unique, two people familiar with the matter said on Friday, which could be key to their decision on Microsoft’s $26 billion bid for the social network.

The European Commission earlier this week sent questionnaires to third parties, asking for their views on the subject after Microsoft sought approval for its biggest ever acquisition.

One of the questions asked whether LinkedIn’s lnkd data from its 433 million professionals is unique and whether it can be replicated, and to what extent substitutes exist for LinkedIn, the people said.

The questionnaire also seeks information on social and professional networks and to what extent artificial intelligence is integrated into customer relationship management that makes business processes quicker and simpler.

Commission spokesman Ricardo Cardoso declined to comment. The EU competition enforcer is scheduled to rule on the deal by Nov. 22. This can be extended by 10 working days if Microsoft @msft offers concessions in the event the Commission has concerns.

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Microsoft is expected to fend off any regulatory worries by citing social network Facebook’s fb vast number of users and competition from other social networks on smartphones.

The deal has drawn criticism from U.S. software rival Salesforce.com crm , which cited the threat to innovation and competition.