Question: Which of the following RLC sublayer functions is **NOT** exclusive to Acknowledged Mode (AM) data transfer, but is also supported for Unacknowledged Mode (UM) data transfer?
Option 1: Error correction through ARQ
Option 2: Duplicate detection
Option 3: RLC SDU discard
Option 4: Re-segmentation of RLC SDU segments
Explanation: The correct answer is Option 3 because, according to the provided functions, "RLC SDU discard" is supported for both UM (Unacknowledged Mode) and AM (Acknowledged Mode) data transfers. In contrast, Options 1, 2, and 4 are either exclusively or additionally mentioned in the context of AM data transfer, highlighting their specific application to acknowledged mode, whereas RLC SDU discard applies broadly across both modes for efficient resource management in telecom networks.