What is the Lewis model for chemical bonding?

The model considers only valence electrons.
The rest of the electrons form a new core with a positive charge.
A single bond between two atoms is formed by the simultaneous attraction of two electrons by the two cores.
The model assumes that the bonds are individualized and formed by pairs of singular electrons.
a) Only statements 1 and 2 are correct.
b) Only statements 2 and 3 are correct.
c) Only statements 1, 3, and 4 are correct.
d) All statements are correct.