Answer: Option (A) is the correct answer.
Explanation:
Elements that belong to the same group show similar chemical properties.
This is because elements that lie in the same group have same number of valence electrons. Hence, they tend to show same type of reactivity which makes them exhibit similar chemical properties.
For example, all alkali metals are very reactive in nature as all of them contain 1 valence electron.
Therefore, in a group pattern of outer electrons is repeating.
Thus, we can conclude that a repeating pattern of outer electrons is the arrangement which is represented in the periodic table.
