What can an anion indicate about an element's behavior?

An anion is formed when an atom gains one or more electrons, which gives it a negative charge. This behavior indicates that the element has a strong tendency to accept electrons during chemical reactions, leading to a full valence shell and achieving stability in accordance with the octet rule. The formation of anions is a common behavior among nonmetals, which typically have high electronegativities. Thus, the correct answer demonstrates an essential aspect of anions' role in chemical reactivity and bonding, highlighting their tendency to gain valence electrons to achieve a more stable electronic configuration.