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 correct answer as to what the Aufbau principle states is B. electrons will be added to an atom starting from the lowest possible level or sublevel. First, these lowest levels have to be fulfilled before going into the higher levels of energy, in order to make the matter balanced and in harmony, until the perfect electron configuration is achieved - the one which is stable. The word Aufbau is a German word that means "building-up."

Hope you find the answer