a) an atom that has either gained or lost electron(s)
Explanation:
A neutral atom is an atom that has equal numbers of protons and electrons, its charge is neutral. These atoms are not stable (exceptions are the noble gases), so they need to gain, lose or share electrons to be stable.
When an atom gains or loses electrons, it became an ion, and its charge will not be more neutral. If it gains electrons (which are negative particles) it will have a negative charge and will be called anion; if it loses electrons, it will have a positive charge and will be called cation.
