Which statement is true regarding escutcheon plates used with recessed or flush-type sprinklers?

The correct statement regarding escutcheon plates used with recessed or flush-type sprinklers is that they do not need to be listed as part of the assembly. Escutcheon plates serve as decorative coverings that conceal the space between the sprinkler head and the ceiling, primarily for aesthetic purposes. While they play a role in the overall appearance and installation of the sprinkler system, their specific listing with the assembly is not a mandatory requirement.

In many circumstances, sprinklers can function effectively without requiring the escutcheon plate to be part of the listed components, allowing for variability in terms of design and style choices made by installers. This provides flexibility as long as the overall performance and safety standards of the sprinkler system are maintained.

The other options are not accurate because escutcheon plates may not always be visible if they are designed to fit flush against the ceiling, they are not strictly optional since installation can be guided by aesthetic choices and local codes, and they are not mandated to be installed in every installation scenario.