Which of the following statements best explains why elements in the same group of the Periodic Table exhibit similar chemical properties?

Elements in the same group have the same number of valence electrons, which determines how they share or take electrons when they react. Because the valence shell is identical, the elements behave similarly, forming similar types of bonds and reacting in comparable ways. For example, all halogens have seven valence electrons, so chlorine and fluorine both like to gain one electron to become stable ions. This shared electronic structure explains why the halogens are all highly reactive and form similar compounds. Thus, the common valence electron count is the key reason for the similar chemical properties of a group.