According to NFPA 72, which statement is true regarding household fire alarm systems?

The statement regarding smoke detection circuits not being required to lock in is in line with NFPA 72, which outlines the requirements for fire alarm systems, including those for households. In residential fire alarm systems, smoke detectors can be designed to activate a notification device without requiring a locking mechanism that keeps the activation signal active. This allows for a more straightforward operation, where the alarm can restart after being cleared, such as when the smoke clears and does not require a complicated reactivation process. This provision is made to enhance the usability of these systems in everyday situations, particularly where easy accessibility and straightforward operation are essential.

In contrast, while reset switches being required to latch (as mentioned in another option) could be true for some system types, it is not a general requirement unique to household systems under NFPA 72 guidelines. Similarly, while monitoring of Notification Appliance Circuits (NACs) may be emphasized in larger or more complex systems, household fire alarm systems often do not carry the same monitoring requirements as commercial systems. Therefore, acknowledging that smoke detection circuits do not necessarily need to implement a lock-in feature helps clarify the overall flexibility and design intent in household fire alarm systems according to NFPA 72 standards.