In an on-network group call of an MCPTT group which is a constituent MCPTT group of a temporary MCPTT group, which keys protect the media sent and received by an MCPTT client and a user homed in the IWF?
GMK and GMK-ID
SRTP-MK, SRTP-MS, and SRTP-MKI
SRTP-MK and SPK
PCK and PCK-ID
SPK and SPK-ID