What does the aufbau principle state?
a. electrons will be added to an atom in a random order.
b. electrons will be added to an atom starting from the lowest possible level or sublevel.
c. electrons will be added to an atom in a symmetrical manner.
d. electrons will be added to an atom only if the orbitals are different colors.
e. electrons will be added to an atom in order of their size.

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.