An employee who both orders and receives merchandise is violating which of the following principles?

Audit control refers to the procedures and mechanisms put in place to ensure compliance, accuracy, and integrity of financial reporting. While important, this choice does not directly address the specific issue of an employee handling both ordering and receiving, which is more a matter of responsibility segregation rather than oversight or auditing processes.

Unity of command is a management principle stating that each employee should report to only one supervisor to avoid confusion and conflicting instructions. This principle does not relate to the scenario of ordering and receiving merchandise, as it focuses more on hierarchical structure rather than the distribution of duties within a transaction.

Delegation of duty involves assigning responsibilities to others, which can be part of effective management. However, in the context of this question, the issue lies in the delegation being insufficiently separated between roles, rather than the act of delegation itself. This choice does not capture the core problem of overlapping responsibilities.