You have a hybrid deployment of Exchange Server 2013 and Microsoft Office 365.
The network does not have Active Directory Federation Services (AD FS) 2.0 installed.
A user named User1 reports that he cannot access his mailbox because his account is locked out.
You verify that the mailbox of User1 is hosted on Office 365.
You need to unlock the account of User1.
Which cmdlet should you run?

A.
Set-MailUser

B.
Set-MSolUser

C.
Set-Mailbox

D.
Set-ADUser

Explanation:
Applies To: Office 365, Windows Azure, Windows Intune
The Set-MsolUser cmdlet is used to update a user object.
Parameters include:
-BlockCredential <Boolean>
When true, the user will not be able to sign in using their user ID.
Incorrect:
Not C: Set-Mailbox
Use the Set-Mailbox cmdlet to modify the settings of an existing mailbox.
Applies to: Exchange Server 2013, Exchange Online