HELP NEEDED ASAP IM CONFUSED i don't know ANY OF THEM

1)visible light is defined as the wavelengths that are visible to most human eyes. EM radiation is transmitted in waves or particles at different wavelengths and frequencies. Visible light falls in the range of the EM spectrum between infrared (IR) and ultraviolet (UV).

2) In radio waves by changing either the amplitude (AM) or frequency (FM) of the waves. The encoded waves are broadcast from a tower and changed back to sounds by radio receivers.

3) Wavelength is the distance between two corresponding points on adjacent waves. Wavelength is measured in meters and frequency is measured in hertz (Hz), or number of waves per second

Explanation:

the novel is told in flashback