By which function, managers at all levels can ensure that activities are being performed as per the plans ?

Controlling

The correct answer is option (2) : Controlling

Managers at all levels can ensure that activities are being performed as per the plans through the function of Controlling. Controlling involves monitoring, comparing actual performance to planned performance, identifying deviations, and taking corrective actions to ensure that activities are on track and aligned with the established plans and goals. It's a fundamental managerial function that helps maintain order and achieve organizational objectives.