Answer is: B. K and I.
Potassium (K) and iodine (I) will form ionic compound (salt) potassium iodide (KI).
Iodine (nonmetal) attracts electron and it has negative charge and sodium (metal) has positive charge.
Electronegativity (χ) is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.
Atoms with higher electronegativity attracts more electrons towards it, electrons are closer to that atom.