Question: What is primarily transported between Node B and RNC via the Iub interface for a single User Equipment (UE) in the context of uplink E-DCH?
Option 1: One MAC-d flow corresponding to one E-DCH data stream, with the possibility of multiple streams per UE.
Option 2: All MAC-d flows for all UEs served by Node B, aggregated into a single E-DCH data stream.
Option 3: Only signaling information related to HARQ retransmissions and frame numbering for all UEs.
Option 4: Downlink E-DCH transport frames from RNC to Node B.
Explanation: This is correct because the Iub interface transports uplink E-DCH transport frames, with each stream corresponding to one MAC-d flow for a single UE, and a UE can have multiple such streams, aligning with efficient resource management in UTRAN architecture.