Final answer:
Police officers are expected to follow agency policies regarding reporting incidents of domestic violence, even if they occur off-duty. Trooper A likely has an obligation to report Trooper B's conduct to his chain of command.
Step-by-step explanation:
The question concerns whether Trooper A is obligated to report the incident of Trooper B slapping his wife, especially considering that it happened while they were both off-duty. Generally, police officers have a duty to act not only as enforcers of the law but also as citizens who are subject to it. The seriousness of domestic violence cannot be understated, and most law enforcement agencies have policies that dictate reporting such incidents, even if they involve fellow officers. Moreover, an officer's professional responsibilities often extend beyond their on-duty hours, particularly when witnessing a crime. Therefore, it would typically be expected that Trooper A report this incident to his chain of command to ensure it is properly investigated and that necessary actions are taken to address the incident and protect the victim.