Which three of the following test methods are used to ensure that the smoke detectors...

To verify that smoke detectors are operating within their listed sensitivity range, NFPA 72 provides three approved testing methods. These ensure proper functionality and compliance with safety requirements.

NFPA 72 (2022), Section 14.4.4.3.1:

"Sensitivity shall be checked using any of the following methods:

(1) Calibrated test method approved by the authority having jurisdiction

(2) Listed control equipment arranged for the purpose

(3) Calibrated sensitivity test instrument of the smoke detector manufacturer"

The option "test approved by the engineer" isnot listedamong the approved sensitivity test methods in NFPA 72, and therefore is not acceptable for compliance.