Question: During the RRC Connection Suspend procedure, if the eNB receives a fresh {NH, NCC} pair from the MME, what action does the eNB take regarding its AS security context keys (KRRCint, KeNB, KRRCenc, KUPenc)?
Option 1: The eNB keeps all AS security context keys (KRRCint, KeNB, KRRCenc, KUPenc) unchanged.
Option 2: The eNB deletes KRRCint and keeps the other AS security context keys (KeNB, KRRCenc, KUPenc).
Option 3: The eNB keeps KRRCint and KeNB but deletes KRRCenc and KUPenc.
Option 4: The eNB keeps KRRCint but deletes the other AS security context keys (KeNB, KRRCenc, KUPenc).
Explanation: According to the specified behavior for RRC Connection Suspend, when the eNB has a fresh {NH, NCC} pair from the MME, it retains only the KRRCint key for future use and deletes the other keys (KeNB, KRRCenc, KUPenc) of the AS security context after sending the suspend message to the UE. This ensures security by updating and limiting the exposure of sensitive keys while maintaining continuity through KRRCint.