Your network contains an Active Directory domain.   You have a server named Server1 that runs Windows Server 2008 R2. Server1 is an enterprise root  certification authority （CA）.   You have a client computer named Computer1 that runs Windows 7.   You enable automatic certificate enrollment for all client computers that run Windows 7.  You need to verify that the Windows 7 client computers can automatically enroll for certificates.  Which command should you run on Computer1（）

• A、certreq.exe retrieve
• B、certreq.exe submit
• C、certutil.exe getkey
• D、certutil.exe pulse