$(5$ points$)$ The lowest energy photon observed in the vibrational spectrum of a certain quantum harmonic oscillator is $1\mathrm{.}2eV.$ What is the energy of a photon emitted in a transition from the $3^{rd}$ excited state to the ground state?

$3\mathrm{.}6eV$

$2\mathrm{.}4eV$

$0eV$

$4\mathrm{.}8eV$