Which statement about an ion is correct?

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An ion is an atom that has a net electric charge because it has gained or lost electrons. The number of protons stays the same, so the element doesn’t change, but the balance between protons (positive charges) and electrons (negative charges) shifts, creating a positive or negative charge. That’s why the statement describing ions forming by gaining or losing electrons to become electrically charged is the best choice. The other ideas don’t fit: having more neutrons than protons describes certain isotopes, not ions; having the same number of protons and electrons would be a neutral atom; and ions aren’t only positively charged—gaining electrons produces negative ions as well.