Your company has an Active Directory domain. The company has two domain controllers named DC1  
and DC2. DC1 holds the schema master role.   
DC1 fails. You log on to Active Directory by using the administrator account. You are not able to transfer  the schema master role.   
You need to ensure that DC2 holds the schema master role.  What should you do（）

You are decommissioning one of the domain controllers in a child domain.  
You need to transfer all domain operations master roles within the child domain to a newly installed  domain controller in the same child domain.  
Which three domain operations master roles should you transfer（）