Answer C is correct. An upgraded database with default or dbo ownership will fall into the dbo schema when upgraded to SQL Server 2005.
For more information, see the following sources:
Chapter 2, "Creating Database Objects"
SQL Server 2005 Books Online: "Installing SQL Server, Upgrading to SQL Server 2005"
"An Overview of SQL Server 2005 for the Database Developer," http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnsql90/html/sql_ovyukondev.asp
"SQL Server 2005 Upgrade Handbook," www.microsoft.com/technet/prodtechnol/sql/2005/sqlupgrd.mspx
Within Microsoft Technet, go to TechNet Home, Products and Technologies, SQL TechCenter Home, SQL Server 2005, SQL Server 2005 Upgrade Handbook.