D. All of the options
Each of the listed factors can impact the activities undertaken by managers:
A. The size of the organisation can influence the complexity of management tasks and the level of formality in processes.
B. The level of the manager (top-level executive vs. first-line supervisor) determines the scope and nature of decisions made, as top-level executives focus on strategic decisions while first-line supervisors handle day-to-day operations.
C. Whether the organisation is for-profit or not-for-profit affects its goals, strategies, and resource allocation, shaping how managers approach their duties.
Therefore, all of these factors collectively impact the actual activities of managers.