Explanation:

Valence Shell Electron Configuration:
Elements in the same column of the periodic table, also known as a group or family, have similar valence shell electron configurations. The valence shell is the outermost energy level of an atom, and the electrons in this shell are involved in chemical bonding. Elements in the same column have the same number of valence electrons, which gives them similar chemical properties. For example, elements in Group 1 (alkali metals) all have one valence electron in the s orbital, while elements in Group 17 (halogens) all have seven valence electrons in the p orbital.

Highest Principal Quantum Number:
The principal quantum number, represented by the symbol "n," describes the energy level or shell of an electron in an atom. Elements in the same column of the periodic table have the same value of the highest principal quantum number. This means that they have the same number of occupied energy levels. For example, elements in Group 2 (alkaline earth metals) all have their valence electrons in the second energy level (n=2), while elements in Group 18 (noble gases) have their valence electrons in the third energy level (n=3).

Number of Nucleons:
Nucleons are the particles found in the nucleus of an atom, which include protons and neutrons. Elements in the same column of the periodic table do not have the same number of nucleons. The number of nucleons, also known as the atomic mass or atomic weight, varies across elements due to differences in the number of protons and neutrons. For example, the atomic mass of hydrogen is 1, while the atomic mass of helium is 4.

Therefore, the correct answer is option 'A', which states that elements in the same column of the periodic table have similar valence shell electron configurations. They have the same number of valence electrons and exhibit similar chemical properties.