Answer:
B. Increase in proportion to the wavelength of a wave.
Explanation:
An electromagnetic spectrum refers to a range of frequency and wavelength that an electromagnetic wave is distributed or extends. The electromagnetic spectrum comprises of gamma rays, visible light, ultraviolet radiation, x-rays, radio waves, and infrared radiation.
Electromagnetic waves is a propagating medium used in all communications device to transmit data (messages) from the device of the sender to the device of the receiver.
Generally, the most commonly used electromagnetic wave technology in telecommunications is radio waves.
Radio waves can be defined as an electromagnetic wave that has its frequency ranging from 30 GHz to 300 GHz and its wavelength between 1mm and 3000m. Therefore, radio waves are a series of repetitive valleys and peaks that are typically characterized of having the longest wavelength in the electromagnetic spectrum.
Wavelength is simply the distance from one peak of an electromagnetic wave to the next peak. This distance is also equal to the distance from one trough of a wave to another.
Mathematically, wavelength is calculated using this formula;
Hence, the waves in the electromagnetic spectrum have a speed that increase in proportion to the wavelength of a wave.