In a closed-loop process control system, what term is used to describe the action of measuring the difference between the actual result and the desired result and using that difference to drive the actual result toward the desired result?

Correct Answer: Option B — Feedback

Feedback is the fundamental mechanism in closed-loop control where the output of a system is measured and compared against the desired set point. This difference, or error signal, is then used to adjust the process input to minimize the deviation and maintain the desired system state.