In Earth Science, what are tiered cosmos?

The concept of a tiered cosmos is important for an understanding of the meaning of megalithic structures. ... That includes the physical world, but also religious concepts. An important feature of most (if not all) religions is a tiered cosmos: Many cultures know separate realms for  death and living.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

c) should be the answer.