which two scenarios is a create bearer request sent from the SGW to the SGSN on the S4 interface?

In which two scenarios is a create bearer request sent from the SGW to the SGSN on the S4
interface? (Choose two.)

A.
secondary PDP context activation procedure

B.
network-requested secondary PDP context activation procedure

C.
network-triggered service request procedure

D.
when downlink data arrives for the released bearers

E.
PGW restart restoration procedure