Wavelength is defined as:

• A. The space occupied by one cycle.
• B. The rate at which vibration occurs in an EM field during transmitter operations.
• C. The time duration of a single cycle.
• D. The angular frequency of the signal.

Answer: (A)

Wavelength is the spatial length of one complete cycle of a wave—the distance over which the wave pattern repeats in space. In an electromagnetic wave, this is the distance from one point of the cycle to the same point on the next cycle (for example, from crest to crest). The relationship to frequency comes from the wave’s speed: wavelength equals speed divided by frequency. In vacuum, speed is the speed of light, so wavelength = c / f.

The other descriptions don’t fit because they refer to temporal or rate properties rather than spatial extent. The rate at which the field vibrates in time is frequency, not a length. The time duration of a single cycle is the period. Angular frequency describes how quickly the phase changes in radians per second, which is a temporal measure, not a spatial length.