Describe what happens to the size of atoms of the elements as you go across a row and down a column in the periodic table. explain why each of these trends exists

Atom size increases down a group because there is an increase in the number of shells so the attraction between electrons and protons decreases. Atom size decreases across a period because the number of protons increases meaning that there is more attraction between the protons and electrons therefore drawing the outer shells closer to the nucleus.

The answer to the question is d