Question

determine what all of the elements in a set of points have in common.
they are all in the same period (row) on the periodic table.
they dont have anything in common.
they are all in the same group (column) on the periodic table.

Explanation:

Step1: Analyze the first option

Elements in the same period (row) on the periodic table have the same number of electron shells. But this is not what is generally emphasized as a common property for all elements in a set when the question is about a general commonality in terms of group - period structure.

Step2: Analyze the second option

This is incorrect. Elements in a set (either in the same group or same period) have some common properties.

Step3: Analyze the third option

Elements in the same group (column) on the periodic table have the same number of valence electrons. This is a very important and fundamental common property for elements in the same group.

Answer:

They are all in the same group (column) on the periodic table.