Answer:
C- non-metal to non-metal
Explanation:
A "covalent bond" is a bond between two atoms in which the electronegativity difference is not large enough so that the electrons appear to transfer completely to one atom (which is then considered an "ionic" bond).
The nonmetals (right side of the metalloids and hydrogen) are those that can form covalent bonds, because their outer shells are close enough to being full that they readily join with other nonmetals so that the shared electron pairs are sufficient to "fill" their valence shell.
