Question: What triggers the measurement of successful Secondary Node Additions without SN terminated bearers in E-UTRAN?
Option 1: Transmission by the MN of an SgNB reconfiguration complete message to SN after receiving RRCConnectionReconfigurationComplete message from UE.
Option 2: Receipt of SgNB Addition Trigger Indication excluding SN change, inter-eNB HO, intra-eNB HO.
Option 3: Successful handover between eNodeBs.
Option 4: Establishment of a new EPS bearer.
Explanation: The correct answer is Option 1 because the measurement of successful Secondary Node Additions without SN terminated bearers is triggered by the transmission by the MN of an SgNB reconfiguration complete message to SN after receiving RRCConnectionReconfigurationComplete message from UE, as specified in the text. This indicates that the measurement is taken when the secondary node addition is successfully completed without terminating any bearers on the SN.