What is the tenth order to the sentry related to?

The tenth order to the sentry is primarily about saluting all officers as well as colors and standards that are not cased. This order emphasizes the importance of displaying respect and military courtesy when encountering officers and certain flags during duty. Saluting is a fundamental aspect of military protocol that reinforces discipline and hierarchy within the ranks. By acknowledging officers and honors due to national symbols, sentries uphold the traditions and values of the military service.

The other options, while related to sentry duties, do not align with the specific directive of the tenth order. Responding to calls from other sentries, ensuring no unauthorized entries, and practicing drill commands are important aspects of a sentry's responsibilities, but they do not directly pertain to the formal requirements of saluting, which is what the tenth order explicitly governs.