Final answer:
In the military, the senior officer is the last to enter a vehicle or small boat and the first to leave, following a protocol that ensures safety and respect for hierarchy.
Step-by-step explanation:
When military personnel enter automobiles and small boats, they do so in reverse order of rank. This custom is followed to ensure the safety and respect for the hierarchy within the military ranks. According to this protocol, the senior officer will be the last to enter the vehicle and the first to leave it. The correct answer is B) Last first. This is done to ensure that the senior officer is protected by the presence of subordinates when entering and is the most readily available in a situation requiring leadership when exiting.