It's crucial to notify the fire investigator if which of the following is obstructed?

Notifying the fire investigator about obstructions in doors and means of egress is essential because these features are critical for safe evacuation during a fire. The means of egress, including exits and pathways to reach them, must be clear to allow occupants to escape quickly and safely. If these routes are obstructed, it can severely hinder evacuation efforts, potentially leading to injuries or loss of life. The fire investigator needs this information to understand the fire dynamics and the challenges faced by individuals during the incident.

While obstructions to other elements like fire extinguishers or fire alarms are also important, they primarily impact firefighting efforts and early warning systems rather than direct evacuation. Walls and ceilings, while significant in terms of structural integrity and fire spread, do not play the same critical role in terms of immediate human safety as doors and means of egress do.