Which OSI reference model layer provides flow control, sequencing, and acknowledgments?

The Transport layer provides reliable, ordered delivery of data between hosts. TCP, operating at this layer, uses sequence numbers to reorder segments, acknowledgments to confirm receipt, and windowing for flow control - making it the definitive OSI layer for these three functions.

The Data Link layer (Layer 2) handles framing, MAC addressing, and error detection within a single network segment, not end-to-end flow control or sequencing.

The Session layer (Layer 5) manages dialog control and session establishment, maintenance, and termination between applications, not flow control or acknowledgments.

The Presentation layer (Layer 6) is responsible for data formatting, encryption, and compression to prepare data for the Application layer, not sequencing or acknowledgments.