Pauli exclusion principal says no two electrons can have same set of quantum number since for our distant universe three such electrons exist hence the correct answer for this is 3.
since we have 3 spin quantum number the configuration will be 1s3 2s3 2p2.
A noble gas has all orbital filled, first noble gas will have configuration 1s3 2s3 2p6 which means that its atomic number is 3+3+6 = 12
A good explanation is the “Ideal State for Electrons”, like the Noble Gases; but unlike these Noble Gases, with filled outer Shells of electrons, Halogens are -1, and other elements, +1 and so on, so the most stable, and filled electron shells can be created.