Angular width of the central maxima in the Fraunhofer diffraction for λ = 6000 Å is θ0. When the same slit is illuminated by another monochromatic light, the angular width decreases by 30%. The wavelength of this light is,
1
6000 Å
2
420 Å
3
1800 Å
4
4200 Å
5
None of the above/More than one of the above.