Which statement about Cisco SGSN is true?

Which statement about Cisco SGSN is true?

A.
Cisco SGSN adheres to defined 3GPP standards for mobility management, packet data, and accounting

B.
Cisco SGSN can support 2G or 4G Cisco SGSN instance on a single Cisco ASR 5000 system

C.
Cisco SGSN supports 2G or 4G Cisco SGSN instance on a single Cisco ASR 5000 system

D.
Cisco SGSN supports single Cisco SGSN and SGSN instances on multiple Cisco ASR 5000 requests