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.

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.