When calculating total valence electrons, extra electron
pairs are added to the Outside of an atom. The answer is letter C. Suppose you
have a compound of CCl4. You know that chlorine can only share 1 electron
because 7 of its electrons are filled. Also, in carbon, it can only share 4
electrons because 4 of it are already filled. That is why carbon needs four
chlorine to form CCl4.
