Which of the following statements is true about an ion?

An ion is defined as an atom or molecule that has gained or lost one or more electrons, resulting in a net electric charge. When an atom loses electrons, it becomes positively charged and is known as a cation. Conversely, if an atom gains electrons, it becomes negatively charged and is referred to as an anion. Therefore, saying that an ion can be either positively or negatively charged accurately reflects the nature of ions and encompasses both types.

The other statements do not fully capture the characteristics of ions. A claim that ions are always negatively charged is incomplete and misleading, as it ignores cations. Similarly, stating that an ion has a neutral charge is incorrect since that would describe a regular atom that has equal numbers of protons and electrons. Lastly, while some ions can be stable, it is not true that all ions possess stability, as many can be reactive depending on their environment and interactions with other substances.