[单选题]
The diagram shows atomic energy levels of an element, and wavelengths are labeled corresponding to emission for electron transition between certain energy levels.
Which of the following shows these wavelengths in decreasing order?
A. $λ_1,λ_2,λ_3,λ_4$
B. $λ_4,λ_3,λ_2,λ_1$
C. $λ_1,λ_4,λ_3,λ_2$
D. $λ_2,λ_3,λ_4,λ_1$
