Which of the following is an example of a passive fire protection measure?

Passive fire protection measures are designed to contain fires or slow their spread without requiring any action from occupants or fire protection systems. Fire-rated walls and doors serve this purpose by creating barriers that prevent flames and smoke from moving between different areas of a building. This containment helps to protect lives and property during a fire incident.

In contrast, other options like fire alarms, sprinkler systems, and fire extinguishers are classified as active fire protection measures. Fire alarms alert occupants to evacuate, sprinkler systems actively suppress flames by releasing water when heat is detected, and fire extinguishers are used by individuals to actively combat fires. Therefore, while those options play critical roles in fire safety, they do not fit the definition of passive fire protection measures, which are inherently built into the structure itself.