Which statement about message routing and addressing methods is true?

Which statement about message routing and addressing methods is true?

A.
There are three ways to address a message.

B.
The SGSN does not know the subscriber IMSI.
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PassGuide 650-082

C.
Message can be addressed in two ways: by IMSI and by GTT

D.
All configuration areas are required, especially if the routing is based purely on DPC+SSN