What is a common problem with vibration-detection devices used for perimeter security?

A.
They can be defeated by emitting the right electrical signals in the protected area.

B.
The power source is easily disabled.

C.
They cause false alarms by things that do not cause a threat to the environment.

D.
They interfere with computing devices.

Explanation:
This type of system is sensitive to sounds and vibrations and detects
the changes in the noise level of an area it is placed within. This level of
sensitivity can cause many false alarms. These devices do not emit any waves; they
only listen for sounds within an area, and are considered passive devices.