The given answer, C2H3O2-1, represents the acetate ion. Acetate is a negatively charged ion formed when acetic acid, CH3COOH, loses a hydrogen ion. The formula C2H3O2-1 indicates that there are two carbon atoms, three hydrogen atoms, and two oxygen atoms in the acetate ion, with a charge of -1. This ion is commonly found in many compounds and is involved in various chemical reactions.