Question: For which of the following purposes does a UE utilize SystemInformationBlockType18, SystemInformationBlockType19, and SystemInformationBlockType21 for sidelink synchronization in an E-UTRA network?
Option 1: Sidelink Communication, Sidelink Discovery, and V2X Sidelink Communication respectively.
Option 2: Handover Procedures, Cell Selection, and RRC Connection Establishment respectively.
Option 3: Paging, Random Access, and Scheduling Requests respectively.
Option 4: Mobility Management, Session Management, and QoS Control respectively.
Explanation: In the context of E-UTRA, UEs perform sidelink synchronization for various services. Specifically, SystemInformationBlockType18 is used for Sidelink Communication (enabling direct communication between UEs), SystemInformationBlockType19 for Sidelink Discovery (allowing UEs to discover each other), and SystemInformationBlockType21 for V2X (Vehicle-to-Everything) Sidelink Communication (supporting vehicle-related communications).