Through which two procedures does a direct tunnel session change to a two-tunnel session?
(Choose two.)

A.
Iu-release request procedure initiated by RNC

B.
GTPU-error indication by the RNC to the GGSN

C.
UE-initiated secondary PDP context activation

D.
successful GGSN-initiated PDP modification procedure

E.
successful UE-initiated PDP modification procedure

F.
periodic RAU procedure triggered by the UE