In the far field diffraction pattern of a single slit under polychromatic illumination, the first minimum with the wavelength ${\lambda }_1$ is found to be coincident with the third maximum at ${\lambda }_2$ . So 

• A

  $3{\lambda }_1=0.3{\lambda }_2$

• B

  $3{\lambda }_1={\lambda }_2$

• C

  ${\lambda }_1=3.5{\lambda }_2$

• D

  $0.3{\lambda }_1=3{\lambda }_2$