A cavity resonator is

A)
a hollow metallic enclosure
B)
a hollow enclosure having magnetic material as its walls
C)
a hollow enclosure having dielectric material as its walls
D)
None of the above

Correct Answer : Option (A) :   a hollow metallic enclosure


Explanation : Hollow metallic enclosures exhibit resonance behaviour when excited by electromagnetic field.

These enclosures are called cavity resonators.