The term hunting, applied to any mechanism, means that the mechanism:

• A. It overshoots in one direction and reverses past the set point.
• B. Remains fixed at the set point.
• C. Drifts slowly in one direction.
• D. Hums continuously.

Answer: (A)

Hunting is when the control system over-corrects and keeps oscillating around the desired value. If the controller responds too aggressively or with too little damping, it pushes the process variable past the set point in one direction, then reverses and moves past it in the other direction, continuing back and forth until the oscillations die out or the gain is reduced. In HVAC terms, this is seen when temperature control overshoots the set point and then crosses it again, rather than settling exactly at the target.

Staying fixed at the set point would be steady-state control with no oscillation. Drifting slowly in one direction shows a bias rather than a reversal around the set point. A hum describes noise, not the corrective oscillation characteristic of hunting.