Answer:
The central atom in a lewis structure tends to be the least electronegative atom.
Step-by-step explanation:
Lewis structures show each atom and its position in the structure of the molecule using its chemical symbol.
In Lewis structure, the central atom tends to be the least electronegative atom. Usually the central atom will be the one that has the most unpaired valence electrons or least electronegative.
Therefore, the best phrase that completes the sentence is "least electronegative".