Step-by-step explanation:
Picture A which shows an overall negative charge represents an anion. Anion are formed when an atom gains an electron. In doing that, the total number of electrons (negative charge) is greater than the number of protons (positive charge), hence it would have an overall negative charge.
Picture B which shows a neutral charge represents a neutral atom. In an atom, the number of electrons equals the number of protons.
Picture C which shows an overall positive charge represents a cation. Cation are formed when an atom loses an electron. In doing that, the total number of electrons (negative charge) is less than the number of protons (positive charge), hence it would have an overall positive charge.