Which of the following statements are true? A. X.25 is connection‐oriented…

Quick answer: The true statements are that X.25 is connection‑oriented and that Frame Relay provides detection of transmission errors.

• Statement: "X.25 is connection‑oriented network" — True. X.25 establishes virtual circuits (SVCs and PVCs) and provides network‑level flow control and error correction, so communication is connection‑oriented at the network layer.

• Statement: "X.25 doesn’t support switched virtual circuits." — False. X.25 supports both switched virtual circuits (SVCs) and permanent virtual circuits (PVCs).

• Statement: "Frame relay service provides acknowledgements." — False. Frame Relay is designed for speed with minimal network‑level overhead; it does not provide per‑frame acknowledgements or retransmissions and relies on higher‑layer protocols for reliability.

• Statement: "Frame relay service provides detection of transmission errors." — True. Frame Relay uses a Frame Check Sequence (FCS) to detect corrupted frames and typically drops errored frames rather than correcting them at the network layer.

Conclusion: The correct selection is the one that includes only the statements asserting that X.25 is connection‑oriented and that Frame Relay provides detection of transmission errors.