The correct answer is D. All the above.
Unity of command is the principle that each employee should have only one supervisor. This principle helps to ensure that employees are clear about who they are accountable to and that there is no confusion about lines of authority.
Effective control at all levels is the principle that managers should monitor and evaluate the performance of their subordinates and take corrective action when necessary. This principle helps to ensure that employees are meeting expectations and that the organization is achieving its goals.
Delegation of authority is the principle that managers should assign tasks and responsibilities to their subordinates. This principle helps to ensure that managers are not overloaded with work and that employees are given the opportunity to develop their skills.
All three of these principles are essential for the effective functioning of an organization.