Correct Answer:  (4) increasing in atomic number

Why:

The Periodic Table is an arrangement of chemical elements into a tabular form that groups similar elements together and helps demonstrate patterns in the chemical and physical properties of not only known elements but also elements yet to be discovered.

The Table is also organized from lowest atomic number (top Left) to highest (bottom right).  The atomic number of an element represents how many protons the element contains. Remember unless the element is charged the number of protons equals the number of electrons.

The Periodic Table is organized mainly with two trends, Groups and Periods.  Groups are the vertical (up and down) lines of the table and Periods are the horizontal (left and right) lines of the table.  The Period trends represent the maximum number of electrons that can be accommodated in the elements largest electron shell.  For example Row 1 can have two electrons, Row 2: 8 electrons  Row 3: 8 electrons  Row 4:18 electrons Row 5: 18 electrons  The Groups are organized into elements that  exhibit similar physical and chemical properties, and who have the same number of electrons in their outer most shell.

In Summary the Periodic table is organized from lowest atomic number to highest, and is arranged in periods and groups.  Horizontal periods represent the capability of having more electrons in the largest shell and Vertical groups represent having the same number of electrons only in the outer shell making the elements behave similarly.

Answering this question:

You may immediately eliminate choices 1 and 2 because you know that the Periodic table goes from smallest to biggest starting in the Upper Left.  Therefore you know there are no decreasing trends on the periodic table.