Question: What action does a UE perform when it receives a RadioBearerConfig IE that includes an srb3-ToRelease or srb4-ToRelease?
Option 1: Perform SRB addition or reconfiguration as specified in 5.3.5.6.3.
Option 2: Release all SDAP entities established for the PDU sessions and indicate the release of user plane resources to upper layers.
Option 3: Perform DRB release as specified in 5.3.5.6.4.
Option 4: Perform SRB release as specified in 5.3.5.6.2.
Explanation: According to the RadioBearerConfig IE actions, if the UE receives an srb3-ToRelease or srb4-ToRelease, it should perform the SRB release as specified in 5.3.5.6.2. This action is specific to releasing SRBs and does not involve adding or reconfiguring SRBs, releasing SDAP entities, or performing DRB releases.