positive protons. negative neutrons. negative protons and positive electrons. positive protons and negative neutrons.
I gave my students this multiple choice question: The charge of the nucleus of an atom is due to the presence of

Only one answer is correct among these 4 choices:
- positive protons.
- negative neutrons.
- negative protons and positive electrons.
- positive protons and negative neutrons.

Could you tell me which one is correct?

positive protons.