The correct answer is b) neutron.
Neutrons are subatomic particles found in the nucleus of an atom, and they do not carry any electric charge. Protons, also located in the nucleus, have a positive charge, while electrons, which orbit around the nucleus, have a negative charge. The neutral nature of neutrons plays a crucial role in stabilizing the nucleus, as the repulsive forces between positively charged protons could otherwise cause it to fall apart. Thus, understanding the charge of subatomic particles is fundamental to the study of atomic structure and chemistry.