In naming a coordination compound the cation is named first, followed by the anion, and within the complex ion the ligands are named alphabetically before the central metal. Here potassium is the counter cation, and the complex anion contains iron surrounded by six cyanide ligands. Because the complex carries a net negative charge, the metal name takes the Latin-derived ending '-ate', giving 'ferrate'. The oxidation state of iron is found from the overall neutrality: three K^+ contribute +3, six CN^- contribute -6, so iron must be +3. The cyanide ligand is written as 'cyano' (the older accepted form) with prefix 'hexa', producing potassium hexacyanoferrate(III). The choice with iron(II) is wrong because the charge balance demands +3, not +2. 'Tripotassium ferricyanide' is an obsolete trivial name, not IUPAC. The 'hexacyanidoiron(III)' option fails because an anionic complex must use 'ferrate', not 'iron'. This follows the NCERT nomenclature rules directly. Plausibility check: ferricyanide is the well-known +3 species, confirming the oxidation state assignment.