In aClass B circuit, supervision of wiring integrity is accomplished using anEnd-of-Line Resistor (EOLR)at thelast devicein the circuit. This allows the control unit to detect open faults.
NFPA 72 (2022), Section 12.3.4.1:
"Initiating device circuits shall be monitored for integrity by placing an end-of-line device at the last device on the circuit." If the wiring is cut or disconnected before the last device, the panel detects it as a trouble condition.
Correct answer: D. The last detector

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.

Normally, smoke detector sensitivity testing is requiredevery two years, butNFPA 72 allows extension up to five yearsif thedetectors have not experienced frequent nuisance alarmsand accuraterecords of performanceare maintained.
NFPA 72 (2022), Section 14.4.4.3.2:
"Where detectors are cleaned and maintained and where records of nuisance alarms and changes in detector locations are kept, the sensitivity testing interval shall be permitted to be extended to 5 years." Keeping a log of nuisance alarms helps assess the reliability of the detectors over time.
Correct answer: C. Records of nuisance alarms shall be maintained

Before performing any inspection or testing activities, it's critical tonotify all affected parties, including occupants, central stations, and local authorities (as applicable), toprevent accidental dispatch of emergency services. The reason for this is clearly stated inNFPA 72 (2022 Edition), Section 14.2.3.1, which requires notification of all stakeholders before any test.
NFPA 72:2022 - 14.2.3.1
"Prior to any testing,all persons and facilities receiving alarm, supervisory, or trouble signals, and all building occupantsshall benotifiedto preventunnecessary response." This is critical for avoiding disruptions like fire department rollouts or building evacuations that could be triggered by system activations during a test. That makes the correct answer:
D: Unnecessary response

NFPA 72 requiressound pressure level measurementsto verify that audibility meets code requirements. This must be done duringinitial acceptanceandreacceptance testing(e.g., when system changes occur).
NFPA 72 (2022), Section 18.4.7.2:
"Sound pressure level measurements shall be taken and documented during acceptance and reacceptance testing." Correct answer: B. Sound pressure levels are required to be taken during initial acceptance and reacceptance testing.