Question: Upon reception of a STATUS report from the receiving RLC AM entity, what action does the transmitting side of an AM RLC entity take if the report acknowledges (positive or negative) the RLC data PDU with sequence number equal to POLL_SN and t-PollRetransmit timer is running?
Option 1: Start t-Reordering timer for potential reassembly of out-of-order PDUs.
Option 2: Stop and reset t-PollRetransmit timer.
Option 3: Immediately transmit a new STATUS report to confirm receipt of the acknowledgement.
Option 4: Trigger a retransmission of the acknowledged RLC data PDU for redundancy.
Explanation: When the transmitting side of an AM RLC entity receives a STATUS report that acknowledges (either positively or negatively) the RLC data PDU with a sequence number matching POLL_SN, and if the t-PollRetransmit timer is currently running, the appropriate action is to stop and reset this timer. This is because the acknowledgement in the STATUS report fulfills the condition being waited on, thus there's no need for the timer to trigger a retransmission or other actions based on its expiration.