Intrusion system devices located near power lines, electric motors, and unshielded computer cables are susceptible to problems caused by _____.

The correct choice is electromagnetic interference (EMI) because intrusion detection system devices can pick up unwanted signals from their environment, particularly from sources like power lines and electric motors. EMI occurs when electromagnetic fields generated by electrical equipment disrupt the normal operation of nearby electronic devices.

This disruption can lead to false alarms or sensor malfunctions in intrusion detection systems, as these devices may not be designed to filter out such interference. Power lines, electric motors, and unshielded cables can emit substantial electromagnetic noise, making proximity to these sources a critical factor in the reliability of the intrusion detection system's performance.

In contrast, electrical surges primarily concern the sudden increase in voltage in an electrical circuit, which poses a risk to the physical hardware but may not directly lead to the same type of operational disruption as EMI. Signal distortion refers to any alteration of the original shape of a signal, which can be caused by various factors, but EMI specifically relates to interference from electromagnetic sources. Ground loop noise is another type of interference that occurs due to differences in ground potential in electrical systems and is less relevant to the specific context of devices near power lines and motors.