Which of the following pressure sensing mechanisms in a linear-scaled pneumatic indicator is generally used to sense pneumatic pressure as received from a pneumatic pressure transmitter?

Correct Answer: Option C — Bellows

Bellows mechanisms are preferred in pneumatic indicators because they provide sufficient force to drive mechanical linkages across a linear scale. Unlike diaphragms, which are often used for low-pressure differential sensing, bellows offer the necessary travel and linearity required for standard 3-15 psig pneumatic signal processing in instrumentation.