[" C.(ii) and some regions of (iv) "quad " B.only (in) "],[" The simple Bohr model cannot be directly applied to calculate the energy levels of an atom with "],[" electrons.This is because "],[" A.of the electrons not being subject to a central force "],[" B.of screening effects "],[" D.the force between the nucleus and an electron will no longer be given by Coulomb's law "]