Final answer:
The Measuring element is what measures outlet pressure on a regulator, distinct from the restricting, loading, and spring elements, each serving a different function within the regulator's operation.
Step-by-step explanation:
On a regulator, the element responsible for measuring outlet pressure is the B. Measuring element. The measuring element can be a part of various devices designed to detect and indicate the pressure value, as seen in the aneroid gauge example where flexible bellows connected to a mechanical indicator are used to measure pressure. Analogously, in the field of regulation, the measuring element serves the role of sensing the pressure and typically relays this information to other parts of the regulator for appropriate action.
To provide further clarity, the regulating device may have different components with specialized functions. A restricting element (such as a valve) controls flow, the loading element (normally a spring or external pressure) applies force to the restricting element, and a spring element might be part of the loading mechanism that provides the necessary force or feedback.