Answer:
b. Fe-O
Explanation:
A way to predict melting points for ionic compounds is with electronegativity.
Electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.
The most electronegativity difference (E.D.), the highest melting point, thus:
E.D. Al-N = 3,0 - 1,6 = <em>1,4</em>
E.D. Fe-O = 3,5 - 1,8 = <em>1,7</em>
E.D. W-C = 2,5 - 1,7 = <em>0,8</em>
The most electronegativity difference is from Fe-O, thus, this ionic compound will have the highest melting point.
I hope it helps!