Final answer:
Unity of command is a true principle stating that each employee should have only one superior to whom they directly report, ensuring a clear chain of command within an organization. Therefore, the correct option is A.
Step-by-step explanation:
The concept of unity of command is a key principle in organizational management, which states that each employee should report to and be directed by only one manager. This is to avoid any confusion and conflict that could arise from receiving orders from multiple superiors. As it stands, the statement that all employees should answer to only one superior is indeed true. In the context of a hierarchy of authority within a company like Walmart, this principle ensures a clear chain of command. Employees receive instructions from their respective managers, who themselves are accountable to their own superiors, culminating in the CEO who answers to the board of directors and the shareholders. This structured management system exemplifies the application of unity of command.