Why do gamma rays have no charge?

A. they are not made of protons, neutrons, or electrons

B. they have equal numbers of protons and neutrons

C. they are constantly emitting all their protons and electrons

This is because gamma rays are not made of protons, neutrons and electrons. It's an electromagnetic radiation emitted during radioactive process in the form of light. Since light is a quanta called photons and photons have no charge, gamma rays are chargeless.

Gamma rays is just a high energy photon of light. It has no mass or charge. So your best answer is A