Question: What is the primary difference between handover of a PDU Session procedure between 3GPP and untrusted non-3GPP access, and that between 3GPP and trusted non-3GPP access?
Option 1: The type of N3IWF used in the handover procedure.
Option 2: The substitution of untrusted non-3GPP access with a trusted non-3GPP access point (TNAP) and the use of TNGF instead of N3IWF.
Option 3: The activation of PDU Session over untrusted non-3GPP access instead of trusted non-3GPP access.
Option 4: The registration procedure via untrusted non-3GPP access.
Explanation: According to the specifications, handover of a PDU Session between 3GPP and trusted non-3GPP access is supported with modifications and clarifications, including substituting untrusted non-3GPP access with a TNAP and using TNGF instead of N3IWF. This highlights the key differences in handling trusted vs untrusted non-3GPP accesses during handover procedures.