What is the correct order of the electromagnetic spectrum from longest to shortest wavelength?

The correct order of the electromagnetic spectrum from longest to shortest wavelength is indeed represented by the second option.

The electromagnetic spectrum is arranged based on the wavelength of the waves, where longer wavelengths correspond to lower frequencies and shorter wavelengths correspond to higher frequencies. Radio waves have the longest wavelengths, which can range from a few millimeters to kilometers. Following radio waves, microwaves come next, with shorter wavelengths compared to radio. Next in the spectrum is infrared radiation, followed by visible light, which is the portion of the spectrum that can be perceived by the human eye. Beyond visible light, ultraviolet radiation has even shorter wavelengths, followed by X-rays which are shorter still, and finally, gamma rays, which possess the shortest wavelengths in the electromagnetic spectrum.

This order helps in understanding various applications of electromagnetic waves, such as communication technologies using radio waves and medical imaging using X-rays. It exemplifies how different types of electromagnetic radiation can have vastly different properties and uses based on their wavelengths.