What is the fifth order to the sentry regarding their post?

The correct statement regarding the fifth order to the sentry emphasizes the importance of remaining at the assigned post until a proper changeover occurs. This instruction is crucial within military protocol because it ensures that the post remains monitored and secure at all times. Quitting the post without being properly relieved can lead to security breaches and compromises the effectiveness of the watch, which is vital for safety and operational efficiency.

The other options reflect different orders that deal with a sentry's conduct or responsibilities, such as reporting violations and remaining alert. However, they do not specifically pertain to the order that addresses the necessary protocol for leaving a post, which is why they are not the fifth order to the sentry. Recognition of the chain of command and adherence to orders is essential, particularly in a military context, where each duty is designed to uphold order and security.