Final answer:
The key management functions are planning, organizing, leading, and controlling, which are essential tasks that managers carry out to achieve organizational objectives.
Step-by-step explanation:
The key management functions are A) Planning, organizing, leading, and controlling. These are fundamental tasks that managers at all levels perform. Planning involves setting objectives and determining a course of action to achieve them. Organizing is the process of allocating resources and tasks and arranging them in a structure to accomplish the plan. Leading means motivating and directing the people involved in the plan to ensure their cooperation. Lastly, controlling involves monitoring the progress towards the plan's goals and making adjustments as necessary.