Question: What type of procedures must a relay node support according to the Evolved Packet System (EPS) specifications?
Option 1: All procedures that are mandatory for a UE supporting S5/S8 mode only.
Option 2: All procedures that are mandatory for a UE supporting S1 mode only.
Option 3: Only procedures specific to relay nodes, excluding those applicable to UEs.
Option 4: Procedures that are optional for UEs but mandatory for relay nodes.
Explanation: According to the EPS specifications, a relay node must support all procedures that are mandatory for a UE supporting S1 mode only. This ensures that relay nodes can operate seamlessly within the network and provide the necessary functionality for user equipment (UEs) connected through them.