Waveguides and radiation

Which of the following transitions is NOT allowed in the case of an atom, according to the electric dipole radiation selection rule?...

Consider a state described by $\Psi(x, t) = \psi_2(x, t) + \psi_4(x, t)$, where $\psi_2(x, t)$ and $\psi_4(x, t)$ are respectively the second and fourth normalized harmonic oscilla...