You have a SharePoint Server 2007 Service Pack 2 (SP2) server farm. The farm contains four servers. The servers are configured as shown in the following table.

You plan to perform an in-place upgrade of the farm to SharePoint Server 2010 Service Pack 1 (SP1).

You need to identify which software must be upgraded before you perform the upgrade.

Which software should you identify? (Each correct answer presents part of the solution. Choose all that apply.)

A.
the operating system on APP1

B.
the operating system on SQL1

C.
the operating system on WFE2

D.
SQL Server 2005 SP3 on SQL1

E.
the operating system on WFE1