Which UL signaling option is referenced as a multiplex digital arm communicator?

• A. Direct wire
• B. McCulloh transmitter
• C. Multiplex digital arm communicator
• D. One way radio

Answer: (C)

The question tests recognizing UL signaling option names and which one is described as a multiplex digital arm communicator. In UL documentation, a multiplex digital arm communicator is the signaling path that sends alarm data as a digital, multiplexed stream over a single channel, allowing more information to be transmitted efficiently to the monitoring station. This differentiates it from a direct wire, which is a simple hardwired connection, and from one-way radio, which transmits in one direction without back-channel capabilities. The McCulloh transmitter is a different signaling device and not the labeled multiplex digital option. So the term that matches the description exactly is multiplex digital arm communicator.