Which of the following is a type of ancillary function in fire alarms?

Background music serves as a type of ancillary function in fire alarm systems because it is not directly related to life safety or the functions of fire detection or suppression, but rather enhances the overall environment of a building. Ancillary functions are those that support the primary fire alarm system while not being essential for the alerting of occupants in case of a fire emergency.

In many commercial applications, background music can be part of a broader sound system that also integrates with the fire alarm system to provide announcements or alerts as needed. However, its primary role is to provide a pleasant auditory atmosphere rather than to indicate an emergency situation.

Other options like emergency alerts and fire evacuation signals are integral to the fire alarm's primary functions of warning individuals during a fire emergency, while automatic fire suppression is a critical system in extinguishing fires, not ancillary to fire alarms but rather a complementary safety measure.