Your network contains an Active Directory domain named contoso.com. All servers run Windows Server 2012
R2. The domain contains a domain controller named DC1 that is configured as an enterprise root certification
authority (CA).
All users in the domain are issued a smart card and are required to log on to their domain-joined client
computer by using their smart card.
A user named User1 resigned and started to work for a competing company.
You need to prevent User1 immediately from logging on to any computer in the domain.
The solution must not prevent other users from logging on to the domain.
Which tool should you use?

A.
Server Manager

B.
The Certification Authority console

C.
Active Directory Administrative Center

D.
Active Directory Sites and Services