33. Silicon carbide, Sic, has a structure similar to diamond. Boron nitride, BN, has a structure similar to graphite. Bronze is an alloy of copper.
Which statements about silicon carbide, boron nitride and bronze are correct?

I All of these substances are bonded covalently.

II All of these substances have high melting points.

III Boron nitride and bronze can conduct electricity in solid state but not pure
silicon carbide.

A II
B I, II
C I, III
D II, III