What was meant by "lock the door when going to bed" in relationship to Jack's instruction?

The phrase "lock the door when going to bed" signifies the importance of taking a precaution to ensure safety and security during the night. Jack's instruction implies that this action is not just a suggestion but a crucial step to protect oneself and the household. By emphasizing the need to lock the door, it communicates a sense of responsibility and the potential consequences of neglecting such a measure. Thus, understanding this instruction within the context of protecting a living space underscores its importance, making the choice that reflects this notion as the best answer.