Answer:
B) Electrons and protons
Explanation:
Each proton has a positive charge, and each electron has a negative charge. If the atom is electrically neutral, there must be the same number of electrons and protons.
A) and C) are wrong. Neutrons have no charge, so they can't counteract that of the protons or the electrons.
D) is wrong. The atomic number is the number of protons, and the mass number is the number of protons plus neutrons. The neutrons can't counteract the charge of the protons,