The correct answer to the question is : C) By their wavelength
EXPLANATION:
Before going to answer this question, first we have to understand the electromagnetic spectrum.
An electromagnetic wave is the transverse wave which contains time varying electric field and magnetic field which are perpendicular to each other as well as perpendicular to the direction of propagation.
There are various electromagnetic waves which are named as gamma ray, X-ray, U.V ray, visible light, infrared wave, micro wave and radio waves respectively. Out of these waves, only visible light can be visualized by human eye.
Every electromagnetic wave is characterized by its wavelength. Different waves have different range of wavelength.
The electromagnetic spectrum is the the arrangement of electromagnetic waves either in ascending order of wavelength or in descending order.
The gamma ray has the minimum wavelength in the spectrum, and radio wave has the maximum wavelength.
The energy carried by electromagnetic waves having wavelength is calculated as-
Energy =
Here, c is the velocity of light and h is the Planck' s constant.
Hence, the correct answer to the question is wavelength which will signify the energy of different types of electromagnetic waves.