Question: What is the primary distinction between how RLC data PDUs are handled in Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM) RLC entities, in terms of interaction with peer entities?
Option 1: The main difference lies in whether the receiving entity acknowledges receipt of RLC data PDUs to the transmitting entity (Acknowledged for AM, not acknowledged for UM and TM).
Option 2: The primary distinction is in the logical channels used for delivering RLC data PDUs to lower layers, which vary by mode.
Option 3: The key difference is in the formation of RLC SDUs from received RLC data PDUs, with AM handling this process differently than UM and TM.
Option 4: There is no distinction in how RLC data PDUs are handled among these modes regarding interaction with peer entities; differences lie elsewhere.
Explanation: The correct answer highlights the fundamental difference in how these RLC modes operate, particularly concerning acknowledgment of received data. Acknowledged Mode (AM) involves the receiving entity sending acknowledgments back to the transmitting entity for received RLC data PDUs, which is not a feature of Unacknowledged Mode (UM) or Transparent Mode (TM). This distinction impacts reliability and retransmission handling in each mode, making it crucial for understanding their applications in telecom networks.