Answer:
D. All of the above
Explanation:
Elements are being grouped in the "Periodic Table" in order to associate them with other elements that have similar properties. These elements also have the same number of "valence electrons" or electrons located in the outer shell. The groups are then classified into their "family names." For example, Group 1 is named "Alkali metals" because the elements within it are very reactive and have high conductive property. The valance electron of the elements in this group is "1."
