HOTSPOT
You have an Office 365 subscription that has a site collection with a URL of https://contoso.sharepoint.com.
Users report that they are prevented from uploading documents to the site because of free space issue. You increase the storage quota for the site collection to 1000 MB.
You need to ensure that you receive a warning message when the site collection uses 90 percent of the available space.
What command should you run? To answer, select the appropriate options in the answer area.
NOTE: Each correct selection is worth one point.
Hot Area:
megabytes of the site collection to warn the site collection administrator that the site is approaching the storage quota.
Answer: 
Explanation:
Box1
The Set-SPOSite cmdlet is used to set or updatesone or more properties’ values for a site collection.
Box2
The -Identity parameter of the Set-SPOSite cmdlet specifies the URL of the site collection to update.
Box3
The -StorageQuotaWarningLevel parameter of the Set-SPOSite cmdlet specifies the warning level in
References: https://technet.microsoft.com/en-us/library/fp161394.aspx