Answer:
4 energy levels/rings
Step-by-step explanation:
By the atomic model proposed by Niels Bohr, the electrons orbit around the nucleus in shells having different energy level each with the ability to contain a given maximum amount of electrons.
The closest shell to the nucleus named the K shell, can have a maximum of two electrons, the next shell known as the L shell can have 8 electrons while the next shell, M, can have a maximum of 18 electrons
The arrangement of the periodic table is based on the number and location of electrons such that elements in the 4th row (period 4 elements) have three completed energy levels/rings before, their valence ring making the total number of rings = 4 energy levels/rings.