__________ is a bit-oriented protocol for communication over point-to-point…

Answer: HDLC — High-Level Data Link Control is a bit-oriented protocol for communication over point-to-point and multipoint links.

Key features:

• Bit-oriented framing using the flag sequence 01111110 and bit-stuffing to delimit frames reliably.

• Support for both point-to-point and multipoint (multi-drop) link configurations.

• Provides flow and error control and operates in modes such as Normal Response Mode (NRM), Asynchronous Response Mode (ARM), and Asynchronous Balanced Mode (ABM).

• Forms the basis for other link-layer implementations and can carry higher-layer protocols.

Why the other choices are not correct:

• Stop-and-wait is an ARQ technique that sends one frame at a time and waits for an acknowledgement; it is a retransmission/flow-control method, not the complete bit-oriented protocol described.

• Sliding window is a flow-control and error-control mechanism allowing multiple outstanding frames; it is used within link-layer protocols (for example, HDLC) but is not itself the specific bit-oriented protocol.

• Go-back-N is a particular sliding-window ARQ strategy where multiple frames are retransmitted after an error; it describes a retransmission policy rather than a full bit-oriented link-layer protocol.