Which step is necessary in closing the office?

Locking all doors and windows is a critical step in closing the office as it ensures the security and safety of the premises. This action helps to protect both the physical assets within the office and the sensitive information that may be present. Properly securing the office environment prevents unauthorized access and potential theft or vandalism.

While other actions, like retrieving messages from the answering service or deactivating the alarm system, may be part of the closing procedure, they do not provide the same level of security for the office as ensuring that all entry points are securely shut and locked. Additionally, waiting for everyone to leave illustrates a teamwork approach to closing procedures but does not directly address the immediate security of the office. Therefore, locking all doors and windows stands out as a necessary and fundamental step to safeguard the office when closing for the day.