Electromagnetic waves are composed of

repelling electrons and neutrons

protons emitted by stationary electrons

photons emitted by moving electrons

protons and neutrons

Photons emitted by moving electrons.

Explanation:

Moving electron produces a photon. Electrons emit photons when it moves from higher energy state to lower energy state. light is a bunch of photons.

Since light is an electromagnetic wave. And carries photon which has no mass but energy. And that energy is related to frequency of electromagnetic wave.

So, electromagnetic waves must be composed of photons emitted by moving electrons.

an ion is a charged atom or molecule. it is charged because the number of electrons do not equal the number of protons in the atom or molecule. an atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.

the entire statement is true and correct.  

there's no diagram, nothing is illustrated, and no question is asked.