What is used for one-way transmission?

• A. One Conductor
• B. Two Conductors
• C. Coaxial Cable
• D. Shielded Cable

Answer: (A)

The idea being tested is that one-way transmission can be achieved with a single conductor by using the Earth as the return path. In this setup, the signal travels along one wire, and the current returns through the ground instead of a separate conductor. This works for simple or low-frequency signaling and can reduce wiring, but it relies on a good, low-impedance earth connection and is more susceptible to noise.

Coaxial and shielded cables inherently involve a second conductor (the outer shield or shield plus conductor) to provide a return path and to shield the signal from interference. That makes them suitable for controlled, often bidirectional or higher-fidelity transmission, rather than inherently one-way use.