Which of the following filled thermal systems used as a temperature transmitting/receiving system usually is associated with a display with a non-uniform scale?

Correct Answer: Option C — Vapor-pressure systems

Vapor-pressure systems operate on the principle of liquid-vapor equilibrium within a closed bulb. Because the pressure-temperature relationship is non-linear, following the Clausius-Clapeyron relation, the resulting scale on the display is non-uniform, unlike gas-filled systems which follow Charles's Law and exhibit a linear response.