Which of the following is NOT a quality that a pressure gauge should display?

Answer: C — Electrical resistance

A pressure gauge serves specific functions related to measuring and displaying various pressures associated with gas systems. In the context of CNG, the pressure gauge typically shows readings such as storage pressure and fuel supply cylinder fill pressure. These measurements are crucial for ensuring that the system operates within safe and efficient pressure limits. The display of electrical resistance by a pressure gauge does not pertain to pressure measurements at all. Electrical resistance is related to the flow of electricity within a circuit and is not a relevant quality for a device designed to measure gas pressure. Therefore, the correct answer focuses on a quality that is outside the intended function of a pressure gauge.