HOTSPOT
You upgrade a SharePoint 2010 environment to SharePoint 2013. The new environment
includes the following site collections.
All site collections are backward compatible with SharePoint 2010.
You are preparing to allow site owners to upgrade sites to SharePoint 2013 compatibility
mode. You need to limit the number of sites that can be upgraded concurrently to five or
fewer. Which Windows PowerShell cmdlets should you run? (To answer, select the
appropriate cmdlet from each drop-down list in the answer area.)
Answer: 
Explanation:
The answer is false, it should be Get-SPContentDatabase, not ‘Set’.
But there is no good answer here.
https://technet.microsoft.com/en-us/library/ff191199.aspx
it should be:
$var = Get-SPContentDatabase WSS_Content
$var.ConcurrentSiteUpgradeSessionLimit = 5
or
$var = Get-SPWebApplication “http://intranet.contoso.com”
$var.SiteUpgradeThrottleSettings.AppPoolConcurrentUpgradeSessionLimit = 5
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