Question: What is a key requirement for a 5G system when a roaming User Equipment (UE) activates a service/application requiring a network slice not offered by the serving network but available in the area from other networks?
Option 1: The serving network must provide an alternative service/application to the UE.
Option 2: The Home Public Land Mobile Network (HPLMN) must block the UE's access to the required service/application.
Option 3: The serving network must automatically switch the UE to a different network slice.
Option 4: The HPLMN shall provide the UE with prioritization information of the Visited Public Land Mobile Networks (VPLMNs) with which the UE may register for the network slice.
Explanation: This requirement ensures seamless service continuity for roaming UEs by enabling informed decisions about registering with alternative VPLMNs that offer the required network slice, thus minimizing service interruption and enhancing user experience. This aligns with the 5G system's goal of optimizing resource utilization and providing flexible, adaptive connectivity solutions.