Answer/Explanation:
A 3 to 5-minute steady tone typically represents (c) Secure all doors.
In many emergency situations, such as a fire or a lockdown, a steady alarm tone is used to signal occupants to secure all doors and take appropriate safety measures. This helps to prevent the spread of fire, smoke, or intruders and enhances the safety of individuals within the building. Therefore, a 3 to 5-minute steady tone often indicates the need to secure all doors as part of emergency protocols.
