When migrating from Cisco Unified Communications Manager Release 5.x to Release 6.x, what is the fastest way to assign line appearances to users?

A.
Manually edit each user account from a line-based user to a line-appearance-based user.

B.
Use Cisco Unified Communications Manager BAT to migrate users from line-based users to line-appearance-based users.

C.
Delete and reprovision users to have line-appearance mappings.

D.
The upgrade automatically handles the migration from line-based user to line-appearance-based user.