Consider the transitions involving only the n=1 through n=5 energy levels of the Bohr model of a hydrogen atom. Photons of the lowest energy level are emitted in a transition from the level with n=? to the level with n=?
A: n=4 to n=3
B:n=5 to n=4
C:n=3 to n=2
D:n=4 to n=2
E:n=3 to n=4