Hello I took this test just now and got 100% your correct answer would be C. Hope this helps.
Radio waves
Radio waves, on the other hand, have the lowest energies, longest wavelengths, and lowest frequencies of any type of EM radiation. In order from highest to lowest energy, the sections of the EM spectrum are named: gamma rays, X-rays, ultraviolet radiation, visible light, infrared radiation, and radio waves.
Yes cytoplasm is about 80% of water and usually colourless
