In Young's double-slit experiment, two different light beams of wavelengths λ₁ and λ₂ produce interference pattern with band widths β₁ and β₂ respectively. If the ratio between β₁ and β₂ is 3:2, then the ratio between λ₁ and λ₂ is

A. 3 : 1
B. 1 : 3
C. 2 : 3
D. 3 : 2