Question: What triggers the increment of the successful outgoing intra-eNB/RN handovers per handover cause measurement in E-UTRAN?
Option 1: Receipt of a RRC message RRCConnectionReconfiguration sent from the eNB/RN to the UE.
Option 2: Transmission of a S1AP message HandoverRequest from the source eNB/RN to the target eNB/RN.
Option 3: Receipt of a RRC message RRCConnectionReconfigurationComplete sent from the UE to the target (=source) eNB/RN.
Option 4: Detection of radio link failure in the serving cell.
Explanation: The correct answer is Option 3 because, according to the text, each RRCConnectionReconfigurationComplete message transmitted from the UE to the target (=source) eNB/RN is added to the relevant per handover cause measurement, indicating a successful outgoing intra-eNB/RN handover.