Strict liability applies when a manufacturer or service provider is held legally responsible for damages or injuries caused by a defective product or service, regardless of fault or intent. This type of liability is often associated with consumer protection laws, where the focus is on the danger posed to the user rather than negligence on the part of the provider.
Plaintiff (B) is the party bringing the suit.
Defendant (C) is the party being sued.
"None of the above" (D) is incorrect since "Strict liability" is the correct legal principle.
References:
ASIS POA Manual - Legal Liability in Security Operations
PSP Study Guide - Civil Law and Legal Liability

An alarm sensor (also called a detector or initiating device) detects specific changes such as motion, temperature, or opening/closing of entry points. It is the primary component in any detection system and initiates the alarm response.
References:
ASIS International, Protection of Assets (POA), Chapter: Intrusion Detection and Alarm Systems ASIS PSP Certification Study Manual, Domain 2: Physical Security System Components

Multiplex systems allow multiple alarm signals to be transmitted over a single communication line. This significantly reduces the cost of leasing multiple phone lines while enhancing efficiency and providing a high level of security by encoding and validating data streams.
A (Circuit loop) is an older method using dedicated circuits.
C (Cellular) is wireless but may not always offer secure or low-cost options.
D (Dial-up) is cost-effective but offers limited security and speed.
References:
PSP Study Guide - Alarm System Technologies
POA Manual - Alarm Communication Systems