Answer:
b. Fe-O
Step-by-step 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 = 1,4
E.D. Fe-O = 3,5 - 1,8 = 1,7
E.D. W-C = 2,5 - 1,7 = 0,8
The most electronegativity difference is from Fe-O, thus, this ionic compound will have the highest melting point.
I hope it helps!