In which three scenarios is a Create Session Request sent to the SGW? (Choose three.)
A. Gn/Gp SGSN to S4 SGSN routing area update
B. Gn/Gp SGSN to MME tracking area update procedure
C. UE requested PDN connectivity
D. UE triggered service request
E. ready to STANDBY transition within the network
F. network triggered service request procedure
