For interactive, conversational applications (e.g., terminals, chatty protocols, remote sessions), which type of communication line is best suited to support simultaneous two-way exchange?

Introduction / Context:
Interactive processing (e.g., remote shells, live customer support, collaborative editing) depends on rapid exchange in both directions. The physical/logical properties of the communication line directly affect responsiveness and user experience.

Given Data / Assumptions:

• Application style: conversational, request/response with frequent back-and-forth.
• Goal: minimize latency and avoid turn-taking delays.
• Bandwidth needs may be modest; directionality is critical.

Concept / Approach:
Full-duplex lines allow simultaneous bidirectional transmission, so the user can send while receiving without collision or enforced silence periods. Simplex permits only one-way flow; half-duplex alternates directions, introducing turn-around delays; “narrowband/mixed band” are vague with respect to directionality and often insufficient descriptors of interactive suitability.

Step-by-Step Solution:
Identify the requirement: continuous two-way interaction.Map to line capability: only full-duplex supports simultaneous send/receive.Conclude full-duplex lines best suit interactive processing.

Verification / Alternative check:
Think of phone conversations (full-duplex) versus walkie-talkies (half-duplex with push-to-talk). Interactive computing ideally mirrors the phone model to optimize responsiveness.

Why Other Options Are Wrong:
Simplex: One-way only; cannot support back-and-forth interaction.

Narrowband / mixed band: Do not specify duplex properties; may still be half/single-direction.

None of the above: Incorrect because full-duplex is a well-known solution.

Common Pitfalls:
Confusing bandwidth with interactivity; higher bandwidth does not fix half-duplex turn-taking delays. Duplex capability is the key requirement.

Final Answer:
full-duplex lines