Concept:Controlling is the management function that checks actual performance against planned goals.
Explanation:The manager sets standards and targets.
Actual outcomes are then measured.
Any difference between actual results and planned targets is identified as an error or deviation.
Corrective action is taken to reduce this deviation and bring performance back on track.
Therefore, measuring outcomes and taking corrective action is the essence of controlling.
It is not staffing, organizing, or directing.
Answer:D. controlling