Answer: a. Controlling
Explanation:
The Controlling function in management is meant to ensure that employees in a company are acting in a manner that abides by the standards of the company or organization in question.
It works by managers ensuring that they check that employees are acting in the way they are to act and if they are not, corrective action must be meted out to stop the behavior.
The Secret Service had some embarrassing moments in 2015 with some agents being found drunk on a trip to Europe where they were assigned to President Obama's detail. Had supervisors been making sure that subordinates acted in a manner befitting of the secret service, the acts would have had a significantly less chance of happening.