Question: What is a permissible action for the receiver (sink) of an RTP PDU regarding the Sequence Number in UTRAN Iu interface data transport?
Option 1: The sink must always use the sequence number to correct out-of-sequence delivery without exception.
Option 2: The sink may either ignore the sequence number or utilize it for link quality statistics and/or correcting out-of-sequence packet delivery.
Option 3: The sink is required to send an acknowledgement for every sequence number received, regardless of packet order.
Option 4: The sink must drop all packets with sequence numbers indicating out-of-sequence delivery without further analysis.
Explanation: This option correctly reflects the flexibility given to the receiver (sink) in handling sequence numbers for RTP PDUs. It allows the sink to either disregard the sequence number or use it for analytical purposes (like assessing link quality) and/or for rearranging out-of-sequence packets, ensuring efficient data transport over the UTRAN Iu interface.